Fixation devices, systems and methods for engaging tissue

ABSTRACT

The invention provides devices, systems and methods for tissue approximation and repair at treatment sites. The devices, systems and methods of the invention will find use in a variety of therapeutic procedures, including endovascular, minimally-invasive, and open surgical procedures, and can be used in various anatomical regions, including the abdomen, thorax, cardiovascular system, heart, intestinal tract, stomach, urinary tract, bladder, lung, and other organs, vessels, and tissues. The invention is particularly useful in those procedures requiring minimally-invasive or endovascular access to remote tissue locations, where the instruments utilized must negotiate long, narrow, and tortuous pathways to the treatment site. In addition, many of the devices and systems of the invention are adapted to be reversible and removable from the patient at any point without interference with or trauma to internal tissues.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/899,901 filed May 22, 2013, which is a continuation of U.S. patentapplication Ser. No. 12/636,471, now U.S. Pat. No. 8,500,761, filed Dec.11, 2009, which is a continuation of, and claims the benefit of priorityfrom U.S. application Ser. No. 11/962,654, now U.S. Pat. No. 7,655,015,filed Dec. 21, 2007, which is a divisional of U.S. patent applicationSer. No. 10/441,531, now U.S. Pat. No. 7,563,267, filed May 19, 2003,which is a continuation-in-part of U.S. patent application Ser. No.09/894,463, now U.S. Pat. No. 6,752,813, filed Jun. 27, 2001, which is acontinuation-in-part of U.S. patent application Ser. No. 09/544,930, nowU.S. Pat. No. 6,629,534, filed Apr. 7, 2000, which claims the benefit ofprior U.S. Provisional Patent Application No. 60/128,690, filed on Apr.9, 1999 under 37 CFR §1.78(a), the full disclosures of which are herebyincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to medical methods, devices, andsystems. In particular, the present invention relates to methods,devices, and systems for the endovascular, percutaneous or minimallyinvasive surgical treatment of bodily tissues, such as tissueapproximation or valve repair. More particularly, the present inventionrelates to repair of valves of the heart and venous valves.

Surgical repair of bodily tissues often involves tissue approximationand fastening of such tissues in the approximated arrangement. Whenrepairing valves, tissue approximation includes coapting the leaflets ofthe valves in a therapeutic arrangement which may then be maintained byfastening or fixing the leaflets. Such coaptation can be used to treatregurgitation which most commonly occurs in the mitral valve.

Mitral valve regurgitation is characterized by retrograde flow from theleft ventricle of a heart through an incompetent mitral valve into theleft atrium. During a normal cycle of heart contraction (systole), themitral valve acts as a check valve to prevent flow of oxygenated bloodback into the left atrium. In this way, the oxygenated blood is pumpedinto the aorta through the aortic valve. Regurgitation of the valve cansignificantly decrease the pumping efficiency of the heart, placing thepatient at risk of severe, progressive heart failure.

Mitral valve regurgitation can result from a number of differentmechanical defects in the mitral valve or the left ventricular wall. Thevalve leaflets, the valve chordae which connect the leaflets to thepapillary muscles, the papillary muscles or the left ventricular wallmay be damaged or otherwise dysfunctional. Commonly, the valve annulusmay be damaged, dilated, or weakened, limiting the ability of the mitralvalve to close adequately against the high pressures of the leftventricle.

The most common treatments for mitral valve regurgitation rely on valvereplacement or repair including leaflet and annulus remodeling, thelatter generally referred to as valve annuloplasty. A recent techniquefor mitral valve repair which relies on suturing adjacent segments ofthe opposed valve leaflets together is referred to as the “bow-tie” or“edge-to-edge” technique. While all these techniques can be veryeffective, they usually rely on open heart surgery where the patient'schest is opened, typically via a sternotomy, and the patient placed oncardiopulmonary bypass. The need to both open the chest and place thepatient on bypass is traumatic and has associated high mortality andmorbidity.

For these reasons, it would be desirable to provide alternative andadditional methods, devices, and systems for performing the repair ofmitral and other cardiac valves. Such methods, devices, and systemsshould preferably not require open chest access and be capable of beingperformed either endovascularly, i.e., using devices which are advancedto the heart from a point in the patient's vasculature remote from theheart or by a minimally invasive approach. Further, such devices andsystems should provide features which allow repositioning and optionalremoval of a fixation device prior to fixation to ensure optimalplacement. Still more preferably, the methods, devices, and systemswould be useful for repair of tissues in the body other than heartvalves. At least some of these objectives will be met by the inventionsdescribed hereinbelow.

2. Description of the Background Art

Minimally invasive and percutaneous techniques for coapting andmodifying mitral valve leaflets to treat mitral valve regurgitation aredescribed in PCT Publication Nos. WO 98/35638; WO 99/00059; WO 99/01377;and WO 00/03759.

Maisano et al. (1998) Eur. J. Cardiothorac. Surg. 13:240-246; Fucci etal. (1995) Eur. J. Cardiothorac. Surg. 9:621-627; and Umana et al.(1998) Ann. Thorac. Surg. 66:1640-1646, describe open surgicalprocedures for performing “edge-to-edge” or “bow-tie” mitral valverepair where edges of the opposed valve leaflets are sutured together tolessen regurgitation. Dec and Fuster (1994) N. Engl. J. Med.331:1564-1575 and Alvarez et al. (1996) J. Thorac. Cardiovasc. Surg.112:238-247 are review articles discussing the nature of and treatmentsfor dilated cardiomyopathy.

Mitral valve annuloplasty is described in the following publications.Bach and Bolling (1996) Am. J. Cardiol. 78:966-969; Kameda et al. (1996)Ann. Thorac. Surg. 61:1829-1832; Bach and Bolling (1995) Am. Heart J.129:1165-1170; and Bolling et al. (1995) 109:676-683. Linear segmentalannuloplasty for mitral valve repair is described in Ricchi et al.(1997) Ann. Thorac. Surg. 63:1805-1806. Tricuspid valve annuloplasty isdescribed in McCarthy and Cosgrove (1997) Ann. Thorac. Surg. 64:267-268;Tager et al. (1998) Am. J. Cardiol. 81:1013-1016; and Abe et al. (1989)Ann. Thorac. Surg. 48:670-676.

Percutaneous transluminal cardiac repair procedures are described inPark et al. (1978) Circulation 58:600-608; Uchida et al. (1991) Am.Heart J. 121: 1221-1224; and Ali Khan et al. (1991) Cathet. Cardiovasc.Diagn. 23:257-262.

Endovascular cardiac valve replacement is described in U.S. Pat. Nos.5,840,081; 5,411,552; 5,554,185; 5,332,402; 4,994,077; and 4,056,854.See also U.S. Pat. No. 3,671,979 which describes a catheter fortemporary placement of an artificial heart valve.

Other percutaneous and endovascular cardiac repair procedures aredescribed in U.S. Pat. Nos. 4,917,089; 4,484,579; and 3,874,338; and PCTPublication No. WO 91/01689.

Thoracoscopic and other minimally invasive heart valve repair andreplacement procedures are described in U.S. Pat. Nos. 5,855,614;5,829,447; 5,823,956; 5,797,960; 5,769,812; and 5,718,725.

BRIEF SUMMARY OF THE INVENTION

The invention provides devices, systems and methods for tissueapproximation and repair at treatment sites. The devices, systems andmethods of the invention will find use in a variety of therapeuticprocedures, including endovascular, minimally-invasive, and opensurgical procedures, and can be used in various anatomical regions,including the abdomen, thorax, cardiovascular system, heart, intestinaltract, stomach, urinary tract, bladder, lung, and other organs, vessels,and tissues. The invention is particularly useful in those proceduresrequiring minimally-invasive or endovascular access to remote tissuelocations, where the instruments utilized must negotiate long, narrow,and tortuous pathways to the treatment site. In addition, many of thedevices and systems of the invention are adapted to be reversible andremovable from the patient at any point without interference with ortrauma to internal tissues.

In preferred embodiments, the devices, systems and methods of theinvention are adapted for fixation of tissue at a treatment site.Exemplary tissue fixation applications include cardiac valve repair,septal defect repair, vascular ligation and clamping, laceration repairand wound closure, but the invention may find use in a wide variety oftissue approximation and repair procedures. In a particularly preferredembodiment, the devices, systems and methods of the invention areadapted for repair of cardiac valves, and particularly the mitral valve,as a therapy for regurgitation. The invention enables two or more valveleaflets to be coapted using an “edge-to-edge” or “bow-tie” technique toreduce regurgitation, yet does not require open surgery through thechest and heart wall as in conventional approaches. Using the devices,systems and methods of the invention, the mitral valve can be accessedfrom a remote surgical or vascular access point and the two valveleaflets may be coapted using endovascular or minimally invasiveapproaches. While less preferred, in some circumstances the inventionmay also find application in open surgical approaches as well. Accordingto the invention, the mitral valve may be approached either from theatrial side (antegrade approach) or the ventricular side (retrogradeapproach), and either through blood vessels or through the heart wall.

The devices, systems and methods of the invention are centered onvariety of devices which may be used individually or in a variety ofcombinations to form interventional systems. In preferred embodiments,the interventional system includes a multi-catheter guiding system, adelivery catheter and an interventional device. Each of these componentswill be discussed herein.

In an exemplary embodiment, the invention provides a fixation devicehaving a pair of distal elements (or fixation elements), each distalelement having a free end and an engagement surface for engaging thetissue, wherein the distal elements are moveable between a firstposition for capturing the tissue and a second position for fixing thetissue. Preferably, the engagement surfaces are spaced apart in thefirst position and are closer together and generally face toward eachother in the second position. The fixation device is preferablydelivered to a target location in a patient's body by a deliverycatheter having an elongated shaft, a proximal end and a distal end, thedelivery catheter being configured to be positioned at the targetlocation from a remote access point such as a vascular puncture orcut-down or a surgical penetration. In a preferred embodiment, thetarget location is a valve in the heart.

The fixation device is preferably delivered with the distal elements ina delivery position configured to minimize the profile of the device.When approaching the mitral valve from the atrial side, some embodimentsof the fixation device allow the device to be delivered with the freeends of the distal elements pointing in a generally proximal directionforming an angle of less than about 90°, preferably less than about 20°,relative to the longitudinal axis of the delivery device shaft. In thisposition the engagement surfaces are facing generally toward each other,being disposed at an angle of less than about 180°, and preferably lessthan about 40°, relative to each other. For ventricular approaches, inthe delivery position the free ends of the distal elements are pointingin a generally distal direction and form an angle of less than about90°, preferably less than about 20° relative to the longitudinal axis ofthe delivery device shaft. In this position, the engagement surfaces arefacing generally toward each other, usually being disposed at an angleof less than about 180°, and preferably less than about 90°, relative toeach other. Alternatively, in some ventricular approaches, it may bepreferred to have the free ends of the fixation elements pointing in agenerally proximal direction and the engagement surfaces facing awayfrom each other in the delivery position.

In order to provide for the reversibility and removability of thedevices and systems of the invention, the distal elements preferably aremovable to an inverted position that minimizes entanglement andinterferences with surrounding tissues should the device be desired tobe withdrawn. In mitral repair applications, this is particularlyimportant due to the presence of chordae tendonae, valve leaflets andother tissues with which devices may become entangled. For approachesfrom the atrial side of the mitral valve, in the inverted position, thefree ends will be pointing in a generally distal direction relative tothe catheter shaft and the engagement surfaces will be facing generallyaway from each other, usually being disposed at an angle of more thanabout 180°, and preferably more than 270°, relative to each other. Forventricular approaches to the valve, in the inverted position the freeends will be pointing in a distal direction relative to the cathetershaft and the engagement surfaces will be facing generally toward eachother, usually being disposed at an angle of less than about 180°, andpreferably less than 90°, relative to each other.

In the open position, the engagement surfaces of the distal elementspreferably form an angle of up to 180° relative to each other so as tomaximize the area in which to capture the valve leaflets or other targettissue. The distal elements are preferably movable to a closed positionin which the engagement surfaces engage each other or form an angle assmall as 0° relative to each other. The distal elements are configuredto be adjusted to and left permanently in any of various positionsbetween the open and closed positions to allow for fixation of tissuesof various thickness, geometry, and spacing.

In a preferred embodiment, the fixation device of the invention willfurther include at least one proximal element (or gripping element).Each proximal element and distal element will be movable relative toeach other and configured to capture tissue between the proximal elementand the engagement surface of the distal element. Preferably, the distalelements and proximal elements are independently movable but in someembodiments may be movable with the same mechanism. The proximal elementmay be preferably biased toward the engagement surface of the fixationelement to provide a compressive force against tissue capturedtherebetween.

In another aspect, the invention provides a fixation device for engagingtissue comprising a coupling member configured for coupling a catheterand a pair of distal elements connected to the coupling member, eachdistal element having an engagement surface for engaging the tissue. Thedistal elements are moveable between an open position wherein the distalelements extend radially outwardly facing the engagement surfaces towarda first direction, and an inverted position wherein the distal elementshave rotated away from the first direction facing the engagementsurfaces radially outwardly.

In a further aspect, the distal elements of the invention are adapted toreceive a suture passed through the target tissue. For example, implantpledgets may be detachably mounted to the distal elements so as to bepositionable against a surface of tissue engaged by the distal elements.A suture may then be passed through the tissue and implant pledget,which are supported by the distal element. The implant pledgets are thendetached from the distal elements, which may be withdrawn from the site,and the suture is tensioned and secured to the target tissue. Thedelivery catheter, in this embodiment, will further include a movablefixation tool or penetration element for penetrating the target tissueand the implant pledget. A suture is coupled to the penetration elementand preferably an anchor is attached to the suture. The penetrationelement is movable relative to the catheter to penetrate the targettissue and the implant pledget, bringing with it the suture and anchor.The anchor is configured to deploy into an expanded configuration so asto securely engage the implant pledget opposite the target tissue,retaining the suture therein. For the mitral valve, an implant pledgetand suture may be similarly deployed in both leaflets, and the suturessecured to one another to coapt the leaflets. Thus, in this embodiment,the distal elements are used to deliver implant pledgets and secure themto the target tissue, but are not themselves deployed at the site as inother embodiments. However, following deployment of the implant pledgetsand associated sutures, the distal elements must be withdrawn from thebody. For this purpose, the distal elements are movable to an invertedposition like the embodiments described above to facilitate withdrawingthe device without interference or injury to surrounding tissues.

In some applications such as the repair of the mitral valve, thefixation device is adapted to be detached from the delivery catheter andleft permanently in the patient. In such applications, it is oftendesirable to promote tissue growth around the fixation device. For thispurpose, some or all of the components of the fixation device arepreferably covered with a covering or coating to promote tissue growth.In one embodiment, a biocompatible fabric cover is positioned over thedistal elements and/or the proximal elements. The cover may optionallybe impregnated or coated with various therapeutic agents, includingtissue growth promoters, antibiotics, anti-clotting, blood thinning, andother agents. Alternatively or in addition, some or all of the fixationelement and/or covering may be comprised of a bioerodable, biodegradableor bioabsorbable material so that it may degrade or be absorbed by thebody after the repaired tissues have grown together.

The distal elements and proximal elements will be configured to providehigh retention force so that the fixation device remains securelyfastened to the target tissue throughout the cardiac cycle. At the sametime, the distal and proximal elements will be configured to minimizetrauma to the tissue engaged by them. This allows the fixation device tobe removed from the tissue after initial application without creatingclinically significant injury to the tissue. In order to enhanceretention without creating significant trauma, the proximal elementsand/or the distal elements may have friction-enhancing features on theirsurfaces that engage the target tissue. Such friction-enhancing featuresmay include barbs, bumps, grooves, openings, channels, surfaceroughening, coverings, and coatings, among others. Optionally, magnetsmay be present in the proximal and/or distal elements. Preferably thefriction-enhancing features and the magnets will be configured toincrease the retention force of the distal and proximal elements on thetissue, while not leaving significant injury or scarring if the deviceis removed.

The distal and proximal elements may further have a shape andflexibility to maximize retention force and minimize trauma to thetarget tissue. In a preferred embodiment, the engagement surfaces of thedistal elements have a concave shape configured to allow the proximalelements, along with the target tissue, to be nested or recessed withinthe distal elements. This increases the surface area of the tissueengaged by the distal elements and creates a geometry of tissueengagement that has a higher retention force than a planar engagementsurface. To minimize trauma, the longitudinal edges as well as the freeends of the distal elements are preferably curved outwardly away fromthe engagement surface so that these edges present a rounded surfaceagainst the target tissue. The distal elements and/or the proximalelements may also be flexible so that they deflect to some degree inresponse to forces against the tissue engaged thereby, reducing thechances that the tissue will tear or bruise in response to such forces.

The fixation device will include an actuation mechanism for moving thedistal elements between the open, closed, and inverted positions. Avariety of actuation mechanisms may be used. In an exemplary embodiment,a coupling member connects the fixation device to the delivery catheter,and a stud is slidably coupled to the coupling member. In a “push toclose/pull to open” embodiment, the distal elements are pivotablycoupled to the stud and the actuation mechanism comprises a pair of linkmembers connected between the distal elements and the coupling member,whereby sliding the stud relative to the coupling member pivots thedistal elements inwardly or outwardly into the various positions.Alternatively, in a “push to open/pull to close” embodiment, the distalelements are pivotably coupled to the coupling member and the linksconnected between the distal elements and the stud.

The fixation device of the invention preferably includes a couplingmember that is detachably connectable to the delivery catheter. Thecoupling member may have various constructions, but in an exemplaryembodiment comprises an outer member having an axial channel, the outermember being coupled to one of either the distal elements or theactuation mechanism. An inner member extends slidably through the axialchannel and is coupled to the other of either the distal elements or theactuation mechanism. The delivery catheter will be configured todetachably connect to both the inner member and the outer member. In oneembodiment, the delivery catheter has a tubular shaft and an actuatorrod slidably disposed in the tubular shaft. The junction of the outermember with the tubular shaft comprises a joining line, which may have avariety of shapes including sigmoid curves. The actuator rod extendsfrom the delivery catheter through the axial channel in the outer memberto maintain its connection with the tubular shaft. The actuator rod maybe connected to the inner member by various connection structures,including threaded connections. By detachment of the actuator rod fromthe inner member and retraction of the actuator rod back into thetubular shaft, the outer member is released from the tubular shaft toallow deployment of the fixation device.

In a preferred embodiment, the fixation device further includes alocking mechanism that maintains the distal elements in a selectedposition relative to each other. Because the ideal degree of closure ofthe fixation device may not be known until it is actually applied to thetarget tissue, the locking mechanism is configured to retain the distalelements in position regardless of how open or closed they may be. Whilea variety of locking mechanisms may be used, in an exemplary embodimentthe locking mechanism comprises a wedging element that is movable intofrictional engagement with a movable component of the fixation device toprevent further movement of the distal elements. In embodimentsutilizing the actuation mechanism described above, the component withwhich the wedging element engages may be the coupling member or the studslidably coupled thereto. In one embodiment, the stud passes through anaperture in the coupling member that has a sloping sidewall, and thewedging element comprises a barbell disposed between the sidewall andthe stud.

The fixation device preferably also includes an unlocking mechanism forreleasing the locking mechanism, allowing the distal elements andproximal elements to move. In one embodiment, the unlocking mechanismcomprises a harness coupled to the wedging element of the lockingmechanism to reduce frictional engagement with the movable component ofthe fixation device. In an exemplary embodiment, the harness is slidablycoupled to the coupling member and extends around the wedging element ofthe locking mechanism, whereby the harness can be retracted relative tothe coupling member to disengage the wedging element from the stud.

In a further aspect, the invention provides an interventional systemcomprising a tubular guide having a proximal end, a distal end and achannel therebetween, the distal end of the tubular guide beingdeflectable about a first axis; a delivery catheter positionable throughthe channel, the delivery catheter having a flexible shaft with aproximal end, a distal end, a lumen therebetween, and an actuationelement movably disposed in the lumen; and a fixation device having acoupling member releasably coupled to the distal end of the shaft, afirst distal element movably coupled to the coupling member, and a firstproximal element movable relative to the distal element, the firstdistal element being releasably coupled to the actuation element andmovable therewith, the first distal element and the first proximalelement being adapted to engage tissue therebetween.

The delivery device of the invention is adapted to allow the user todeliver the fixation device to the target site from a remote accesspoint, whether through endovascular or surgical approaches, align thedevice with the target tissue, and to selectively close, open, invert,lock or unlock the distal element. In some embodiments, the deliverydevice will have a highly flexible, kink resistant, torsionally stiffshaft with minimal elongation and high compressive strength. Thedelivery device will also have the movable components and associatedactuators to move the distal elements between the open, closed, andinverted positions, to move the proximal elements into engagement withthe target tissue, to unlock the locking mechanism, and to detach thedistal element from the delivery catheter. In a preferred embodiment,the delivery device comprises a delivery catheter having an elongatedshaft which has an inner lumen. The distal end of the shaft isconfigured for detachable connection to the coupling member of thefixation device. An actuator rod is slidably disposed in the inner lumenand is adapted for detachable coupling to the stud or other component ofthe fixation device that moves the distal elements. A plurality oftubular guides, preferably in the form of metallic or polymeric coils,extend through the inner lumen of the shaft and are typically fixed tothe shaft near its proximal and distal ends but are unrestrainedtherebetween, providing a highly flexible and kink-resistantconstruction. Lines for actuating the proximal elements and theunlocking mechanism of the fixation device extend through these tubularguides and are detachably coupled to the proximal element and unlockingmechanisms. These and other aspects of delivery catheters suitable foruse in the present invention are described in copending application Ser.No. 10/441,687, filed on the same day as the present application, whichhas been incorporated herein by reference.

The delivery catheter may additionally include a tether that isdetachably coupled to a portion of the fixation device for purposes ofretrieval of the device following detachment from the delivery catheter.The tether may be a separate flexible filament extending from thedelivery catheter to the fixation device, but alternatively may be aline coupled to either the unlocking mechanism or the proximal elementand used also for actuating those components. In either case, the tetherwill be detachable from the fixation device so that it may be detachedonce the device has been deployed successfully.

The system of the invention may additionally include a guide thatfacilitates introduction and navigation of the delivery catheter andfixation device to the target location. The guide is preferably tubularwith a channel extending between its proximal and distal ends in whichthe delivery catheter and fixation device may be slidably positioned.The distal end of the guide is steerable, usually being deflectableabout at least one axis, and preferably about two axes. The guide willhave a size, material, flexibility and other characteristics suitablefor the application in which it is being used. For mitral valve repair,the guide is preferably configured to be introduced in a femoral veinand advanced through the inferior vena cava into the heart, across apenetration in the interatrial septum, and into alignment with themitral valve in the left atrium. Alternatively, the guide may beconfigured for introduction in a femoral, axillary, or brachiocephalicartery and advancement through the aorta and aortic valve into theventricle where it is steered into alignment with the mitral valve. In afurther alternative, the guide may be configured for introductionthrough a puncture or incision in the chest wall and through an incisionin the wall of the heart to approach the mitral valve.

In an exemplary embodiment, the guide comprises a multi-catheter guidingsystem which has two components, including an inner tubular member orinner guide catheter and an outer tubular member or outer guidecatheter. The inner tubular member has a distal end deflectable about afirst axis. The outer tubular member has a distal end deflectable abouta second axis. Further, the inner tubular member may be rotatablerelative to the outer tubular member about its longitudinal axis.Mobility in additional directions and about additional axes mayoptionally be provided. Additional aspects of guides usable in thesystem of the invention are described in pending application Ser. No.10/441,508, which has been incorporated herein by reference.

The invention further provides methods of performing therapeuticinterventions at a tissue site. In one embodiment, the method includesthe steps of advancing an interventional tool having a proximal end, adistal end and a fixation device near the distal end to a locationwithin a patient's body, wherein the fixation device includes a pair ofdistal elements each having a free end and an engagement surface; movingthe distal elements to an open position wherein the free ends are spacedapart; positioning the distal elements such that the engagement surfacesengage tissue at the tissue site; and detaching the fixation device fromthe interventional tool. Preferably, the method further includes thestep of inverting the distal elements to an inverted position whereinthe free ends point generally in a distal direction. In someembodiments, the engagement surfaces will face generally away from eachother in the inverted position, while in other embodiments, theengagement surfaces will face generally toward each other in theinverted position.

In an exemplary embodiment, the tissue site comprises first and secondleaflets, and the step of moving the distal elements comprises coaptingthe leaflets. The leaflets may be part of a variety of tissuestructures, but are preferably part of a cardiac valve such as themitral valve. In antegrade approaches, the step of advancing willusually include inserting the fixation device through a valve annulus,e.g. from an atrium of the heart to a ventricle of the heart. In suchapproaches, the method may further include a step of withdrawing thefixation device through the valve annulus with the fixation device inthe inverted position. Retrograde approaches are also provided, in whichthe step of advancing will include the step of passing the fixationdevice through a ventricle of the heart into an atrium of the heart. Thestep of advancing may further comprise transluminally positioning thefixation device through a blood vessel into the heart, and may includeinserting the fixation device through an interatrial septum of theheart. Alternatively, the step of advancing may comprise inserting thedevice through a surgical penetration in a body wall.

The method may further include moving the distal elements to a closedposition after the step of positioning, the free ends of the distalelement being closer together in the closed position with the engagementsurfaces facing generally toward each other. In addition, the method mayinclude a step of deploying a proximal element on the fixation devicetoward each engagement surface to as to capture tissue therebetween.Before the step of inverting, the proximal elements are retracted awayfrom the engagement surfaces. The method optionally includes a step oflocking the distal elements in a desired position, and may furtherinclude a step of unlocking the distal elements so that they are movableagain.

In a further aspect, a method according to the invention comprisesadvancing a catheter having a proximal end, a distal end and a fixationdevice near the distal end to a location within a body, wherein thefixation device includes a pair of distal elements each having anengagement surface; moving the distal elements to an open positionwherein the distal elements extend radially outwardly facing theengagement surfaces toward a direction other than radially outwardly;and moving the distal elements to an inverted position wherein theengagement surfaces face radially outwardly.

In still another aspect, the invention provides a method for fixingtissues together comprising advancing a catheter having a proximal end,a distal end and a fixation device disposed near the distal end to alocation near the tissues, wherein the fixation device includes a pairof distal elements each having a removable implant pledget; moving thedistal elements so that each implant pledget engages one of the tissues;penetrating each tissue and engaged implant pledget and passing a tietherethrough; fastening the ties to fix the tissues together; andremoving the fixation device leaving the implant pledget in place.

In an additional aspect of the invention, kits for performing anintervention at a tissue site in a patient's body include a fixationdevice and Instructions for Use setting forth the steps of using thefixation device according to the methods of the invention. The fixationdevice may be as described in any of the various examples set forthherein. The kits may further include a delivery tool or catheter fordelivering the fixation device to the tissue site, as well as a tubularguide through which the delivery tool or catheter may be positioned.

Other aspects of the nature and advantages of the invention are setforth in the detailed description set forth below, taken in conjunctionwith the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the left ventricle and left atrium of the heartduring systole.

FIG. 2A illustrates free edges of leaflets in normal coaptation, andFIG. 2B illustrates the free edges in regurgitative coaptation.

FIG. 3A-3C illustrate grasping of the leaflets with a fixation device,inversion of the distal elements of the fixation device and removal ofthe fixation device, respectively.

FIG. 4 illustrates the position of the fixation device in a desiredorientation relative to the leaflets.

FIGS. 5A-5B, 6A-6B illustrate exemplary embodiments of couplingmechanisms of the instant application.

FIGS. 7A-7D illustrate an embodiment of a fixation device in variouspositions.

FIGS. 8A-8B illustrate an embodiment of the fixation device wherein someor all of the components are molded as one part.

FIG. 9 illustrates another embodiment of the fixation device of thepresent invention.

FIGS. 10A-10B, 11A-11B, 12A-12B, 13A-13B, 14-16 illustrate embodimentsof a fixation device in various possible positions during introductionand placement of the device within the body to perform a therapeuticprocedure.

FIGS. 17A-17C illustrate a covering on the fixation device wherein thedevice is in various positions.

FIG. 18 illustrates an embodiment of the fixation device includingproximal elements and a locking mechanism.

FIG. 19 provides a cross-sectional view of the locking mechanism of FIG.18.

FIGS. 20-21 provide a cross-sectional view of the locking mechanism inthe unlocked and locked positions respectively.

FIGS. 22A-22B illustrate a variation of the fixation device tofacilitate capture of more widely-separated leaflets or other tissueflaps.

FIGS. 23, 24A-24B illustrate another embodiment of a locking mechanism.

FIGS. 25, 26A-26B illustrate yet another embodiment of a lockingmechanism.

FIGS. 27-28 illustrate an additional embodiment of the fixation devicewherein separation of couplers rotate the distal elements around pins.

FIGS. 29-30 illustrate the fixation device of FIGS. 27-28 withadditional features such as barbs and bumpers.

FIG. 31 illustrates an embodiment of the fixation device havingengagement surfaces with a serrated edge and wherein the fixation deviceis mounted for a ventricular approach to a mitral valve.

FIGS. 32-34 illustrate an additional embodiment of the fixation devicewhich allows tissue to be grasped between the distal elements and theproximal elements while in an arrangement wherein the distal elementsare parallel to each other.

FIGS. 35-39, 40A-40D, 41-42, 43A-43C illustrate another embodiment ofthe fixation device wherein the fixation device includes distal elementshaving implant pledgets.

FIGS. 44A-44B, 45-46 illustrate another embodiment of the fixationdevice wherein the distal elements are comprised of a semi-rigidmaterial having a folded shape.

FIG. 47 is a perspective view of an embodiment of a delivery catheterfor a fixation device.

FIG. 48 illustrates an embodiment of a fixation device coupled to thedistal end of a delivery catheter.

FIG. 49 illustrates a portion of the shaft of a delivery catheter and afixation device which is coupleable with the catheter.

FIGS. 50-52 are cross-sectional views of embodiments of the shaft of thedelivery catheter.

FIGS. 52A-52B illustrate embodiments of the nose of the shaft of thedelivery catheter.

FIG. 53A-53C illustrate various arrangements of lock lines engagingrelease harnesses of a locking mechanism.

FIGS. 54A-54B illustrate various arrangements of proximal element linesengaging proximal elements of a fixation device.

FIG. 55 illustrates an embodiment of the handle of the deliverycatheter.

FIG. 56 is a cross-sectional view of the main body of the handle.

FIG. 57 illustrates an embodiment of a lock line handle.

FIG. 57A illustrates the lock line handle of FIG. 57 positioned within asemi-tube which is disposed within the sealed chamber.

FIGS. 58A-58B illustrate a mechanism for applying tension to lock lines.

FIGS. 59, 59A-59B illustrate features of the actuator rod control andhandle.

FIG. 60 is a perspective view of an embodiment of a multi-catheterguiding system of the present invention, and an interventional catheterpositioned therethrough.

FIG. 61A illustrates a primary curvature in an outer guide catheter.

FIG. 61B illustrates a secondary curvature in an inner guide catheter.

FIGS. 61C-61D illustrate example movement of an inner guide catheterthrough angle thetas.

FIG. 62A is a perspective side view of a multi-catheter guiding systemhaving an additional curve in the outer guide catheter.

FIG. 62B illustrates lifting of the outer guide catheter due to theadditional curve of FIG. 62A.

FIGS. 63A-63D illustrate a method of using the multi-catheter guidingsystem for accessing the mitral valve.

FIGS. 64A-64D illustrate curvature of a guide catheter of the presentinvention by the actuation of one or more pullwires.

FIG. 64E illustrates attachment of a pullwire to a tip ring.

FIGS. 65A-65I illustrate embodiments of the present invention comprisingsections constructed with the inclusion of braiding or coil.

FIGS. 66A-66C illustrate a keying feature of the present invention.

FIGS. 67A-67B are perspective views of a guide catheter including aseries of articulating members.

FIG. 68 illustrates embodiments of the handles.

FIG. 69 illustrates the handles of FIG. 68 with a portion of the housingremoved.

FIG. 70 illustrates steering mechanisms within a handle.

FIG. 71 illustrates attachment of a pullwire to a disk.

FIGS. 72A-72B illustrate a hard stop peg restricting rotation of a disk.

FIGS. 73A-73C illustrates a portion of a hard stop gear assembly.

FIGS. 74A-74F illustrate a ball restricting rotation of a disk.

FIG. 75 illustrates an embodiment of a friction assembly.

FIG. 76 illustrates an embodiment of an interventional system of thepresent invention.

FIG. 76A illustrates an embodiment of a hemostatic valve for use withthe present invention.

FIG. 76B illustrates an embodiment of a fixation device introducer.

FIG. 77 illustrates another embodiment of an interventional system ofthe present invention.

FIGS. 78-80 illustrate an embodiment of a stabilizer base for use withthe present invention.

FIG. 81 illustrates a kit constructed in accordance with the principlesof the present invention

DETAILED DESCRIPTION OF THE INVENTION

I. Cardiac Physiology

The left ventricle LV of a normal heart H in systole is illustrated inFIG. 1. The left ventricle LV is contracting and blood flows outwardlythrough the tricuspid (aortic) valve AV in the direction of the arrows.Back flow of blood or “regurgitation” through the mitral valve MV isprevented since the mitral valve is configured as a “check valve” whichprevents back flow when pressure in the left ventricle is higher thanthat in the left atrium LA. The mitral valve MV comprises a pair ofleaflets having free edges FE which meet evenly to close, as illustratedin FIG. 1. The opposite ends of the leaflets LF are attached to thesurrounding heart structure along an annular region referred to as theannulus AN. The free edges FE of the leaflets LF are secured to thelower portions of the left ventricle LV through chordae tendinae CT(referred to hereinafter as the chordae) which include plurality ofbranching tendons secured over the lower surfaces of each of the valveleaflets LF. The chordae CT in turn, are attached to the papillarymuscles PM which extend upwardly from the lower portions of the leftventricle and intraventricular septum IVS.

A number of structural defects in the heart can cause mitral valveregurgitation. Regurgitation occurs when the valve leaflets do not closeproperly allowing leakage from the ventricle into the atrium. As shownin FIG. 2A, the free edges of the anterior and posterior leafletsnormally meet along a line of coaptation C. An example of a defectcausing regurgitation is shown in FIG. 2B. Here an enlargement of theheart causes the mitral annulus to become enlarged, making it impossiblefor the free edges FE to meet during systole. This results in a gap Gwhich allows blood to leak through the valve during ventricular systole.Ruptured or elongated chordae can also cause a valve leaflet to prolapsesince inadequate tension is transmitted to the leaflet via the chordae.While the other leaflet maintains a normal profile, the two valveleaflets do not properly meet and leakage from the left ventricle intothe left atrium will occur. Such regurgitation can also occur inpatients who have suffered ischemic heart disease where the leftventricle does not contract sufficiently to effect proper closure.

II. General Overview

The present invention provides methods and devices for grasping,approximating and fixating tissues such as valve leaflets to treatcardiac valve regurgitation, particularly mitral valve regurgitation.The present invention also provides features that allow repositioningand removal of the device if so desired, particularly in areas whereremoval may be hindered by anatomical features such as chordae CT. Suchremoval would allow the surgeon to reapproach the valve in a new mannerif so desired.

Grasping will preferably be atraumatic providing a number of benefits.By atraumatic, it is meant that the devices and methods of the inventionmay be applied to the valve leaflets and then removed without causingany significant clinical impairment of leaflet structure or function.The leaflets and valve continue to function substantially the same asbefore the invention was applied. Thus, some minor penetration ordenting of the leaflets may occur using the invention while stillmeeting the definition of “atraumatic”. This enables the devices of theinvention to be applied to a diseased valve and, if desired, removed orrepositioned without having negatively affected valve function. Inaddition, it will be understood that in some cases it may be necessaryor desirable to pierce or otherwise permanently affect the leafletsduring either grasping, fixing or both. In some of these cases, graspingand fixation may be accomplished by a single device. Although a numberof embodiments are provided to achieve these results, a general overviewof the basic features will be presented herein. Such features are notintended to limit the scope of the invention and are presented with theaim of providing a basis for descriptions of individual embodimentspresented later in the application.

The devices and methods of the invention rely upon the use of aninterventional tool that is positioned near a desired treatment site andused to grasp the target tissue. In endovascular applications, theinterventional tool is typically an interventional catheter. In surgicalapplications, the interventional tool is typically an interventionalinstrument. In preferred embodiments, fixation of the grasped tissue isaccomplished by maintaining grasping with a portion of theinterventional tool which is left behind as an implant. While theinvention may have a variety of applications for tissue approximationand fixation throughout the body, it is particularly well adapted forthe repair of valves, especially cardiac valves such as the mitralvalve. Referring to FIG. 3A, an interventional tool 10, having adelivery device, such as a shaft 12, and a fixation device 14, isillustrated having approached the mitral valve MV from the atrial sideand grasped the leaflets LF. The mitral valve may be accessed eithersurgically or by using endovascular techniques, and either by aretrograde approach through the ventricle or by an antegrade approachthrough the atrium, as described above. For illustration purposes, anantegrade approach is described.

The fixation device 14 is releasably attached to the shaft 12 of theinterventional tool 10 at its distal end. When describing the devices ofthe invention herein, “proximal” shall mean the direction toward the endof the device to be manipulated by the user outside the patient's body,and “distal” shall mean the direction toward the working end of thedevice that is positioned at the treatment site and away from the user.With respect to the mitral valve, proximal shall refer to the atrial orupstream side of the valve leaflets and distal shall refer to theventricular or downstream side of the valve leaflets.

The fixation device 14 typically comprises proximal elements 16 (orgripping elements) and distal elements 18 (or fixation elements) whichprotrude radially outward and are positionable on opposite sides of theleaflets LF as shown so as to capture or retain the leafletstherebetween. The proximal elements 16 are preferably comprised ofcobalt chromium, nitinol or stainless steel, and the distal elements 18are preferably comprised of cobalt chromium or stainless steel, howeverany suitable materials may be used. The fixation device 14 is coupleableto the shaft 12 by a coupling mechanism 17. The coupling mechanism 17allows the fixation device 14 to detach and be left behind as an implantto hold the leaflets together in the coapted position.

In some situations, it may be desired to reposition or remove thefixation device 14 after the proximal elements 16, distal elements 18,or both have been deployed to capture the leaflets LF. Suchrepositioning or removal may be desired for a variety of reasons, suchas to reapproach the valve in an attempt to achieve better valvefunction, more optimal positioning of the device 14 on the leaflets,better purchase on the leaflets, to detangle the device 14 fromsurrounding tissue such as chordae, to exchange the device 14 with onehaving a different design, or to abort the fixation procedure, to name afew. To facilitate repositioning or removal of the fixation device 14the distal elements 18 are releasable and optionally invertible to aconfiguration suitable for withdrawal of the device 14 from the valvewithout tangling or interfering with or damaging the chordae, leafletsor other tissue. FIG. 3B illustrates inversion wherein the distalelements 18 are moveable in the direction of arrows 40 to an invertedposition. Likewise, the proximal elements 16 may be raised, if desired.In the inverted position, the device 14 may be repositioned to a desiredorientation wherein the distal elements may then be reverted to agrasping position against the leaflets as in FIG. 3A. Alternatively, thefixation device 14 may be withdrawn (indicated by arrow 42) from theleaflets as shown in FIG. 3C. Such inversion reduces trauma to theleaflets and minimizes any entanglement of the device with surroundingtissues. Once the device 14 has been withdrawn through the valveleaflets, the proximal and distal elements may be moved to a closedposition or configuration suitable for removal from the body or forreinsertion through the mitral valve.

FIG. 4 illustrates the position of the fixation device 14 in a desiredorientation in relation to the leaflets LF. This is a short-axis view ofthe mitral valve MV from the atrial side, therefore, the proximalelements 16 are shown in solid line and the distal elements 18 are shownin dashed line. The proximal and distal elements 16, 18 are positionedto be substantially perpendicular to the line of coaptation C. Thedevice 14 may be moved roughly along the line of coaptation to thelocation of regurgitation. The leaflets LF are held in place so thatduring diastole, as shown in FIG. 4, the leaflets LF remain in positionbetween the elements 16, 18 surrounded by openings O which result fromthe diastolic pressure gradient. Advantageously, leaflets LF are coaptedsuch that their proximal or upstream surfaces are facing each other in avertical orientation, parallel to the direction of blood flow throughmitral valve MV. The upstream surfaces may be brought together so as tobe in contact with one another or may be held slightly apart, but willpreferably be maintained in the vertical orientation in which theupstream surfaces face each other at the point of coaptation. Thissimulates the double orifice geometry of a standard surgical bow-tierepair. Color Doppler echo will show if the regurgitation of the valvehas been reduced. If the resulting mitral flow pattern is satisfactory,the leaflets may be fixed together in this orientation. If the resultingcolor Doppler image shows insufficient improvement in mitralregurgitation, the interventional tool 10 may be repositioned. This maybe repeated until an optimal result is produced wherein the leaflets LFare held in place.

Once the leaflets are coapted in the desired arrangement, the fixationdevice 14 is then detached from the shaft 12 and left behind as animplant to hold the leaflets together in the coapted position. Asmentioned previously, the fixation device 14 is coupled to the shaft 12by a coupling mechanism 17. FIGS. 5A-5B, 6A-6B illustrate exemplaryembodiments of such coupling mechanisms. FIG. 5A shows an upper shaft 20and a detachable lower shaft 22 which are interlocked at a joining lineor mating surface 24. The mating surface 24 may have any shape orcurvature which will allow or facilitate interlocking and laterdetachment. A snuggly fitting outer sheath 26 is positioned over theshafts 20, 22 to cover the mating surface 24 as shown. FIG. 5Billustrates detachment of the lower shaft 22 from the upper shaft 20.This is achieved by retracting the outer sheath 26, so that the matingsurface 24 is exposed, which allows the shafts 20, 22 to separate.

Similarly, FIG. 6A illustrates a tubular upper shaft 28 and a detachabletubular lower shaft 30 which are interlocked at a mating surface 32.Again, the mating surface 32 may have any shape or curvature which willallow or facilitate interlocking and later detachment. The tubular uppershaft 28 and tubular lower shaft 30 form an outer member having an axialchannel. A snuggly fitting rod 34 or inner member is inserted throughthe tubular shafts 28, 30 to bridge the mating surface 32 as shown. FIG.6B illustrates detachment of the lower shaft 30 from the upper shaft 28.This is achieved by retracting the rod 34 to a position above the matingsurface 32 which in turn allows the shafts 28, 30 to separate. Otherexamples of coupling mechanisms are described and illustrated incommonly assigned U.S. Pat. No. 6,752,813, incorporated herein byreference for all purposes.

In a preferred embodiment, mating surface 24 (or mating surface 32) is asigmoid curve defining a male element and female element on upper shaft20 (or upper shaft 28) which interlock respectively with correspondingfemale and male elements on lower shaft 22 (or lower shaft 30).Typically, the lower shaft is the coupling mechanism 17 of the fixationdevice 14. Therefore, the shape of the mating surface selected willpreferably provide at least some mating surfaces transverse to the axialaxis of the a mechanism 19 to facilitate application of compressive andtensile forces through the coupling mechanism 17 to the fixation device14, yet causing minimal interference when the fixation device 14 is tobe released from the upper shaft.

III. Fixation Device

A. Introduction and Placement of Fixation Device

The fixation device 14 is delivered to the valve or the desired tissueswith the use of a delivery device. The delivery device may be rigid orflexible depending on the application. For endovascular applications,the delivery device comprises a flexible delivery catheter which will bedescribed in later sections. Typically, however, such a cathetercomprises a shaft, having a proximal end and a distal end, and afixation device releasably attached to its distal end. The shaft isusually elongate and flexible, suitable for intravascular introduction.Alternatively, the delivery device may comprise a shorter and lessflexible interventional instrument which may be used for trans-thoracicsurgical introduction through the wall of the heart, although someflexibility and a minimal profile will generally be desirable. Afixation device is releasably coupleable with the delivery device asillustrated in FIG. 3A. The fixation device may have a variety of forms,a few embodiments of which will be described herein.

FIGS. 7A-7D illustrate an embodiment of a fixation device 14 in variouspositions or configurations. FIG. 7A illustrates the fixation device 14in a closed configuration for delivery through the patient's vasculatureand, in this example, through the mitral valve. The fixation device 14includes a coupling member 19 which allows detachment of the fixationdevice 14 for implantation. In this example, the coupling member 19 isshown to include the lower shaft 22 and mating surface 24 of FIGS.5A-5B, and therefore the coupling member 19 would function similarly asdescribed above. The fixation device 14 also includes a pair of opposeddistal elements 18, each distal element 18 having an engagement surface50 facing inwardly toward the opposed distal element 18 in the closedconfiguration. Distal elements 18 preferably comprise elongate arms 53,each arm having a proximal end 52 rotatably connected to the couplingmember 19 and a free end 54. Suitable connections for arms 53 tocoupling member 19 include pins, living hinges, or other knownrotational connection mechanisms. In the closed configuration of FIG.7A, free ends 54 point in a first direction such that the arms 53 andengagement surfaces 50 are nearly parallel to each other and to an axis21, and preferably are angled slightly inwardly toward each other. In apreferred embodiment, when tissue is not present between arms 53, thearms 53 may be closed until free ends 54 either touch each other orengage shaft 12 when fixation device 14 is attached thereto, therebyminimizing the profile of the fixation device 14 for passage through adelivery device.

FIGS. 7B-7C illustrate the fixation device 14 in an open positionwherein the engagement surfaces 50 are disposed at a separation angle 56apart, wherein the separation angle 56 is typically up to approximately180 degrees, preferably up to 90-180 degrees, and arms 53 are disposedgenerally symmetrically relative to axis 21. The arms 53 may be moveableto the open position by a variety of actuation mechanisms. For example,a plunger or actuator rod may be advanced through the coupling member19, as indicated by arrow 62, so as to engage a spring or spring loadedactuation mechanism 58 which is attached to the distal elements 18. Byexerting a force against the actuation mechanism 58, the distal elements18 are rotated relative to coupling member 19. The distal elements 18may be held in this open position by the actuator rod against theresistance provided by the spring of the actuation mechanism 58 whichbiases the distal elements 18 toward the closed position of FIG. 7A whenthe distal elements 18 are less than 180 degrees apart. The springloading of the actuation mechanism 58 resists outward movement of theactuation mechanism 58 and urges the device 14 towards the closedposition.

In this embodiment, proximal elements 16 comprise resilient loop-shapedwire forms biased outwardly and attached to the coupling member 19 so asto be biased to an open position shown in FIG. 7C but moveablerotationally inwardly when arms 53 are closed. The wire forms may beflexible enough to be rigidly attached to coupling member 19 andresiliently deflectable inwardly, or they may be attached by arotational coupling such as a pin or living hinge. In use, leaflets LFare positioned between the proximal elements 16 and distal elements 18.Once, the leaflets LF are positioned between the proximal and distalelements 16, 18, the distal elements 18 may be closed, compressing theleaflets between engagement surfaces 50 and proximal elements 18.Depending upon the thickness of the leaflets, the arrangements of theleaflets, the position of the fixation device on the leaflets and otherfactors, the arms 53 may be maintained in the open position of FIG. 7B,moved to the fully closed position of FIG. 7A, or placed in any ofvarious positions in between so as to coapt the leaflets LF and holdthem in the desired position with the desired degree of force. In anycase, the fixation device 14 will remain in place as an implantfollowing detachment from the delivery catheter.

In some situations, as previously mentioned, it may be desirable toreopen the fixation device 14 following initial placement. To reopen thedevice 14, the actuator rod may be readvanced or reinserted through thecoupling member 19 and readvanced to press against the actuationmechanism 58, as previously indicated by arrow 62 in FIG. 7B. Again,such advancement applies a force against the actuation mechanism 58 inthe manner described above thus moving arms 53 outwardly to releaseforce against leaflets and move engagement surfaces 50 away fromproximal elements 16. The leaflets are then free to move relative tofixation device 14. The fixation device 14 may then be repositioned asdesired and the actuator rod retracted to reclose the distal elements 18to coapt the leaflets.

Under some circumstances, it may be further desirable to withdraw thefixation device 14 back through the valve or completely from the patientfollowing initial insertion through the valve. Should this be attemptedwith the clip in the closed or open positions illustrated in FIGS.7A-7C, there may be a risk that arms 53 could interfere or becomeentangled with the chordae, leaflets or other tissues. To avoid this,the fixation element 14 is preferably adapted for inversion of arms 53so that free ends 54 point in a second direction, opposite to the firstdirection in which the free ends 54 pointed in the closed position, eacharm 53 forming an obtuse angle relative to axis 21 as illustrated inFIG. 7D. The arms 53 may be rotated so that the engagement surfaces 50are disposed at a separation angle 56 of up to 360 degrees, andpreferably at least up to 270 degrees. This may be accomplished byexerting a force against actuation mechanism 58 with a push rod orplunger extending through coupling member 19 as described above. In thisembodiment, once the distal elements 18 have rotated beyond 180 degreesapart, the spring loading of the actuation mechanism 58 biases thedistal elements 18 toward the inverted position. The spring loading ofthe actuation mechanism 58 resists outward movement of the actuationmechanism 58 and urges the device 14 towards the inverted position.

With arms 53 in the inverted position, engagement surfaces 50 provide anatraumatic surface deflect tissues as the fixation device is withdrawn.This allows the device to be retracted back through the valve annuluswithout risk of injury to valvular and other tissues. In some cases,once the fixation device 14 has been pulled back through the valve, itwill be desirable to return the device to the closed position forwithdrawal of the device from the body (either through the vasculatureor through a surgical opening).

The embodiment illustrated in FIGS. 7A-7D is assembled from separatecomponents composed of biocompatible materials. The components may beformed from the same or different materials, including but not limitedto stainless steel or other metals, Elgiloy®, nitinol, titanium,tantalum, metal alloys or polymers. Additionally, some or all of thesecomponents may be made of bioabsorbable materials that will be absorbedby surrounding tissues or will dissolve into the bloodstream followingimplantation. It has been found that in mitral valve repair applicationsthe fixation devices of the invention are completely surrounded bytissue within a few months of implantation, after which the devicescould dissolve or be absorbed without negative impact to the repair.

In a further embodiment, some or all of the components may be molded asone part, as illustrated in FIGS. 8A-8B. Here, the coupling member 19,distal elements 18 and actuation mechanism 58 of the fixation device 14are all molded from a polymer material as one moveable piece. FIG. 8Ashows the fixation device 14 in the open position. Advancement of anactuator rod 64 rotates the distal elements 18 relative to the couplingmember 19 by a living hinge or by elastic deformation of the plastic atthe point of connection between the elements 18 and the coupling member19. Typically, this point of connection comprises a thinner segment ofpolymer to facilitate such bending. Likewise, the actuation mechanism 58coupled to the distal elements 18 in the same manner. FIG. 8B shows thefixation device 14 in the inverted position.

FIG. 9 illustrates another embodiment of a fixation device 14. Here, thefixation device 14 is shown coupled to a shaft 12 to form aninterventional tool 10. The fixation device 14 includes a couplingmember 19 and a pair of opposed distal elements 18. The distal elements18 comprise elongate arms 53, each arm having a proximal end 52rotatably connected to the coupling member 19 and a free end 54. Thefree ends 54 have a rounded shape to minimize interference with andtrauma to surrounding tissue structures. Preferably, each free end 54defines a curvature about two axes, one being an axis 66 perpendicularto longitudinal axis of arms 53. Thus, the engagement surfaces 50 have acupped or concave shape to surface area in contact with tissue and toassist in grasping and holding the valve leaflets. This further allowsarms 53 to nest around the shaft 12 in the closed position to minimizethe profile of the device. Preferably, arms 53 are at least partiallycupped or curved inwardly about their longitudinal axes 66. Also,preferably, each free end 54 defines a curvature about an axis 67perpendicular to axis 66 or the longitudinal axis of arms 53. Thiscurvature is a reverse curvature along the most distal portion of thefree end 54. Likewise, the longitudinal edges of the free ends 54 mayflare outwardly. Both the reverse curvature and flaring minimize traumato the tissue engaged therewith.

In a preferred embodiment suitable for mitral valve repair, thetransverse width across engagement surfaces 50 (which determines thewidth of tissue engaged) is at least about 2 mm, usually 3-10 mm, andpreferably about 4-6 mm. In some situations, a wider engagement isdesired wherein the engagement surfaces 50 are larger, for example about2 cm, or multiple fixation devices are used adjacent to each other. Arms53 and engagement surfaces 50 are configured to engage a length oftissue of about 4-10 mm, and preferably about 6-8 mm along thelongitudinal axis of arms 53. Arms 53 further include a plurality ofopenings to enhance grip and to promote tissue ingrowth followingimplantation.

The valve leaflets are grasped between the distal elements 18 andproximal elements 16. In some embodiments, the proximal elements 16 areflexible, resilient, and cantilevered from coupling member 19. Theproximal elements are preferably resiliently biased toward the distalelements. Each proximal element 16 is shaped and positioned to be atleast partially recessed within the concavity of the distal element 18when no tissue is present. When the fixation device 14 is in the openposition, the proximal elements 16 are shaped such that each proximalelement 16 is separated from the engagement surface 50 near the proximalend 52 of arm 53 and slopes toward the engagement surface 50 near thefree end 54 with the free end of the proximal element contactingengagement surface 50, as illustrated in FIG. 9. This shape of theproximal elements 16 accommodates valve leaflets or other tissues ofvarying thicknesses.

Proximal elements 16 include a plurality of openings 63 and scallopedside edges 61 to increase grip on tissue. The proximal elements 16optionally include frictional accessories, frictional features orgrip-enhancing elements to assist in grasping and/or holding theleaflets. In preferred embodiments, the frictional accessories comprisebarbs 60 having tapering pointed tips extending toward engagementsurfaces 50. It may be appreciated that any suitable frictionalaccessories may be used, such as prongs, windings, bands, barbs,grooves, channels, bumps, surface roughening, sintering, high-frictionpads, coverings, coatings or a combination of these. Optionally, magnetsmay be present in the proximal and/or distal elements. It may beappreciated that the mating surfaces will be made from or will includematerial of opposite magnetic charge to cause attraction by magneticforce. For example, the proximal elements and distal elements may eachinclude magnetic material of opposite charge so that tissue is heldunder constant compression between the proximal and distal elements tofacilitate faster healing and ingrowth of tissue. Also, the magneticforce may be used to draw the proximal elements 16 toward the distalelements 18, in addition to or alternatively to biasing of the proximalelements toward the distal elements. This may assist in deployment ofthe proximal elements 16. In another example, the distal elements 18each include magnetic material of opposite charge so that tissuepositioned between the distal elements 18 is held therebetween bymagnetic force.

The proximal elements 16 may be covered with a fabric or other flexiblematerial as described below to enhance grip and tissue ingrowthfollowing implantation. Preferably, when fabrics or coverings are usedin combination with barbs or other frictional features, such featureswill protrude through such fabric or other covering so as to contact anytissue engaged by proximal elements 16.

In an exemplary embodiment, proximal elements 16 are formed frommetallic sheet of a spring-like material using a stamping operationwhich creates openings 63, scalloped edges 61 and barbs 60.Alternatively, proximal elements 16 could be comprised of a spring-likematerial or molded from a biocompatible polymer. It should be noted thatwhile some types of frictional accessories that can be used in thepresent invention may permanently alter or cause some trauma to thetissue engaged thereby, in a preferred embodiment, the frictionalaccessories will be atraumatic and will not injure or otherwise affectthe tissue in a clinically significant way. For example, in the case ofbarbs 60, it has been demonstrated that following engagement of mitralvalve leaflets by fixation device 14, should the device later be removedduring the procedure barbs 60 leave no significant permanent scarring orother impairment of the leaflet tissue and are thus consideredatraumatic.

The fixation device 14 also includes an actuation mechanism 58. In thisembodiment, the actuation mechanism 58 comprises two link members orlegs 68, each leg 68 having a first end 70 which is rotatably joinedwith one of the distal elements 18 at a riveted joint 76 and a secondend 72 which is rotatably joined with a stud 74. The legs 68 arepreferably comprised of a rigid or semi-rigid metal or polymer such asElgiloy®, cobalt chromium or stainless steel, however any suitablematerial may be used. While in the embodiment illustrated both legs 68are pinned to stud 74 by a single rivet 78, it may be appreciated,however, that each leg 68 may be individually attached to the stud 74 bya separate rivet or pin. The stud 74 is joinable with an actuator rod 64(not shown) which extends through the shaft 12 and is axially extendableand retractable to move the stud 74 and therefore the legs 68 whichrotate the distal elements 18 between closed, open and invertedpositions. Likewise, immobilization of the stud 74 holds the legs 68 inplace and therefore holds the distal elements 18 in a desired position.The stud 74 may also be locked in place by a locking feature which willbe further described in later sections.

In any of the embodiments of fixation device 14 disclosed herein, it maybe desirable to provide some mobility or flexibility in distal elements18 and/or proximal elements 16 in the closed position to enable theseelements to move or flex with the opening or closing of the valveleaflets. This provides shock absorption and thereby reduces force onthe leaflets and minimizes the possibility for tearing or other traumato the leaflets. Such mobility or flexibility may be provided by using aflexible, resilient metal or polymer of appropriate thickness toconstruct the distal elements 18. Also, the locking mechanism of thefixation device (described below) may be constructed of flexiblematerials to allow some slight movement of the proximal and distalelements even when locked. Further, the distal elements 18 can beconnected to the coupling mechanism 19 or to actuation mechanism 58 by amechanism that biases the distal element into the closed position(inwardly) but permits the arms to open slightly in response to forcesexerted by the leaflets. For example, rather than being pinned at asingle point, these components may be pinned through a slot that alloweda small amount of translation of the pin in response to forces againstthe arms. A spring is used to bias the pinned component toward one endof the slot.

FIGS. 10A-10B, 11A-11B, 12A-12B, 13A-13B, and FIGS. 14-16 illustrateembodiments of the fixation device 14 of FIG. 9 in various possiblepositions during introduction and placement of the device 14 within thebody to perform a therapeutic procedure. FIG. 10A illustrates anembodiment of an interventional tool 10 delivered through a catheter 86.It may be appreciated that the interventional tool 10 may take the formof a catheter, and likewise, the catheter 86 may take the form of aguide catheter or sheath. However, in this example the termsinterventional tool 10 and catheter 86 will be used. The interventionaltool 10 comprises a fixation device 14 coupled to a shaft 12 and thefixation device 14 is shown in the closed position. FIG. 10B illustratesa similar embodiment of the fixation device of FIG. 10A in a largerview. In the closed position, the opposed pair of distal elements 18 arepositioned so that the engagement surfaces 50 face each other. Eachdistal element 18 comprises an elongate arm 53 having a cupped orconcave shape so that together the arms 53 surround the shaft 12 andoptionally contact each other on opposite sides of the shaft. Thisprovides a low profile for the fixation device 14 which is readilypassable through the catheter 86 and through any anatomical structures,such as the mitral valve. In addition, FIG. 10B further includes anactuation mechanism 58. In this embodiment, the actuation mechanism 58comprises two legs 68 which are each movably coupled to a base 69. Thebase 69 is joined with an actuator rod 64 which extends through theshaft 12 and is used to manipulate the fixation device 14. In someembodiments, the actuator rod 64 attaches directly to the actuationmechanism 58, particularly the base 69. However, the actuator rod 64 mayalternatively attach to a stud 74 which in turn is attached to the base69. In some embodiments, the stud 74 is threaded so that the actuatorrod 64 attaches to the stud 74 by a screw-type action. However, the rod64 and stud 74 may be joined by any mechanism which is releasable toallow the fixation device 14 to be detached from shaft 12.

FIGS. 11A-11B illustrate the fixation device 14 in the open position. Inthe open position, the distal elements 18 are rotated so that theengagement surfaces 50 face a first direction. Distal advancement of thestud 74 relative to coupling member 19 by action of the actuator rod 64applies force to the distal elements 18 which begin to rotate aroundjoints 76 due to freedom of movement in this direction. Such rotationand movement of the distal elements 18 radially outward causes rotationof the legs 68 about joints 80 so that the legs 68 are directly slightlyoutwards. The stud 74 may be advanced to any desired distancecorrelating to a desired separation of the distal elements 18. In theopen position, engagement surfaces 50 are disposed at an acute anglerelative to shaft 12, and are preferably at an angle of between 90 and180 degrees relative to each other. In one embodiment, in the openposition the free ends 54 of arms 53 have a span therebetween of about10-20 mm, usually about 12-18 mm, and preferably about 14-16 mm.

Proximal elements 16 are typically biased outwardly toward arms 53. Theproximal elements 16 may be moved inwardly toward the shaft 12 and heldagainst the shaft 12 with the aid of proximal element lines 90 which canbe in the form of sutures, wires, nitinol wire, rods, cables, polymericlines, or other suitable structures. The proximal element lines 90 maybe connected with the proximal elements 16 by threading the lines 90 ina variety of ways. When the proximal elements 16 have a loop shape, asshown in FIG. 11A, the line 90 may pass through the loop and doubleback. When the proximal elements 16 have an elongate solid shape, asshown in FIG. 11B, the line 90 may pass through one or more of theopenings 63 in the element 16. Further, a line loop 48 may be present ona proximal element 16, also illustrated in FIG. 11B, through which aproximal element line 90 may pass and double back. Such a line loop 48may be useful to reduce friction on proximal element line 90 or when theproximal elements 16 are solid or devoid of other loops or openingsthrough which the proximal element lines 90 may attach. A proximalelement line 90 may attach to the proximal elements 16 by detachablemeans which would allow a single line 90 to be attached to a proximalelement 16 without doubling back and would allow the single line 90 tobe detached directly from the proximal element 16 when desired. Examplesof such detachable means include hooks, snares, clips or breakablecouplings, to name a few. By applying sufficient tension to the proximalelement line 90, the detachable means may be detached from the proximalelement 16 such as by breakage of the coupling. Other mechanisms fordetachment may also be used. Similarly, a lock line 92 may be attachedand detached from a locking mechanism by similar detachable means.

In the open position, the fixation device 14 can engage the tissue whichis to be approximated or treated. The embodiment illustrated in FIGS.9-11 is adapted for repair of the mitral valve using an antegradeapproach from the left atrium. The interventional tool 10 is advancedthrough the mitral valve from the left atrium to the left ventricle. Thedistal elements 18 are oriented to be perpendicular to the line ofcoaptation and then positioned so that the engagement surfaces 50contact the ventricular surface of the valve leaflets, thereby graspingthe leaflets. The proximal elements 16 remain on the atrial side of thevalve leaflets so that the leaflets lie between the proximal and distalelements. In this embodiment, the proximal elements 16 have frictionalaccessories, such as barbs 60 which are directed toward the distalelements 18. However, neither the proximal elements 16 nor the barbs 60contact the leaflets at this time.

The interventional tool 10 may be repeatedly manipulated to repositionthe fixation device 14 so that the leaflets are properly contacted orgrasped at a desired location. Repositioning is achieved with thefixation device in the open position. In some instances, regurgitationmay also be checked while the device 14 is in the open position. Ifregurgitation is not satisfactorily reduced, the device may berepositioned and regurgitation checked again until the desired resultsare achieved.

It may also be desired to invert the fixation device 14 to aid inrepositioning or removal of the fixation device 14. FIGS. 12A-12Billustrate the fixation device 14 in the inverted position. By furtheradvancement of stud 74 relative to coupling member 19, the distalelements 18 are further rotated so that the engagement surfaces 50 faceoutwardly and free ends 54 point distally, with each arm 53 forming anobtuse angle relative to shaft 12. The angle between arms 53 ispreferably in the range of about 270 to 360 degrees. Further advancementof the stud 74 further rotates the distal elements 18 around joints 76.This rotation and movement of the distal elements 18 radially outwardcauses rotation of the legs 68 about joints 80 so that the legs 68 arereturned toward their initial position, generally parallel to eachother. The stud 74 may be advanced to any desired distance correlatingto a desired inversion of the distal elements 18. Preferably, in thefully inverted position, the span between free ends 54 is no more thanabout 20 mm, usually less than about 16 mm, and preferably about 12-14mm. In this illustration, the proximal elements 16 remain positionedagainst the shaft 12 by exerting tension on the proximal element lines90. Thus, a relatively large space may be created between the elements16, 18 for repositioning. In addition, the inverted position allowswithdrawal of the fixation device 14 through the valve while minimizingtrauma to the leaflets. Engagement surfaces 50 provide an atraumaticsurface for deflecting tissue as the fixation device is retractedproximally. It should be further noted that barbs 60 are angled slightlyin the distal direction (away from the free ends of the proximalelements 16), reducing the risk that the barbs will catch on or laceratetissue as the fixation device is withdrawn.

Once the fixation device 14 has been positioned in a desired locationagainst the valve leaflets, the leaflets may then be captured betweenthe proximal elements 16 and the distal elements 18. FIGS. 13A-13Billustrate the fixation device 14 in such a position. Here, the proximalelements 16 are lowered toward the engagement surfaces 50 so that theleaflets are held therebetween. In FIG. 13B, the proximal elements 16are shown to include barbs 60 which may be used to provide atraumaticgripping of the leaflets. Alternatively, larger, more sharply pointedbarbs or other penetration structures may be used to pierce the leafletsto more actively assist in holding them in place. This position issimilar to the open position of FIGS. 11A-11B, however the proximalelements 16 are now lowered toward arms 53 by releasing tension onproximal element lines 90 to compress the leaflet tissue therebetween.At any time, the proximal elements 16 may be raised and the distalelements 18 adjusted or inverted to reposition the fixation device 14,if regurgitation is not sufficiently reduced.

After the leaflets have been captured between the proximal and distalelements 16, 18 in a desired arrangement, the distal elements 18 may belocked to hold the leaflets in this position or the fixation device 14may be returned to or toward a closed position. Such locking will bedescribed in a later section. FIG. 14 illustrates the fixation device 14in the closed position wherein the leaflets (not shown) are captured andcoapted. This is achieved by retraction of the stud 74 proximallyrelative to coupling member 19 so that the legs 68 of the actuationmechanism 58 apply an upwards force to the distal elements 18 which inturn rotate the distal elements 18 so that the engagement surfaces 50again face one another. The released proximal elements 16 which arebiased outwardly toward distal elements 18 are concurrently urgedinwardly by the distal elements 18. The fixation device 14 may then belocked to hold the leaflets in this closed position as described below.

As shown in FIG. 15, the fixation device 14 may then be released fromthe shaft 12. As mentioned, the fixation device 14 is releasablycoupleable to the shaft 12 by coupling member 19. FIG. 15 illustratesthe coupling structure, a portion of the shaft 12 to which the couplingmember 19 of the fixation device 14 attaches. As shown, the proximalelement lines 90 may remain attached to the proximal elements 16following detachment from shaft 12 to function as a tether to keep thefixation device 14 connected with the catheter 86. Optionally, aseparate tether coupled between shaft 12 and fixation device 14 may beused expressly for this purpose while the proximal element lines 90 areremoved. In any case, the repair of the leaflets or tissue may beobserved by non-invasive visualization techniques, such asechocardiography, to ensure the desired outcome. If the repair is notdesired, the fixation device 14 may be retrieved with the use of thetether or proximal element lines 90 so as to reconnect coupling member19 with shaft 12.

In an exemplary embodiments, proximal element lines 90 are elongatedflexible threads, wire, cable, sutures or lines extending through shaft12, looped through proximal elements 16, and extending back throughshaft 12 to its proximal end. When detachment is desired, one end ofeach line may be released at the proximal end of the shaft 12 and theother end pulled to draw the free end of the line distally through shaft12 and through proximal element 16 thereby releasing the fixationdevice.

FIG. 16 illustrates a released fixation device 14 in a closed position.As shown, the coupling member 19 remains separated from the shaft 12 ofthe interventional tool 10 and the proximal elements 16 are deployed sothat tissue (not shown) may reside between the proximal elements 16 anddistal elements 18.

While the above described embodiments of the invention utilize apush-to-open, pull-to-close mechanism for opening and closing distalelements 18, it should be understood that a pull-to-open, push-to-closemechanism is equally possible. For example, distal elements 18 may becoupled at their proximal ends to stud 74 rather than to coupling member19, and legs 68 may be coupled at their proximal ends to coupling member19 rather than to stud 74. In this example, when stud 74 is pusheddistally relative to coupling member 19, distal elements 18 would close,while pulling on stud 74 proximally toward coupling member 19 would opendistal elements 18.

B. Covering on Fixation Device

The fixation device 14 may optionally include a covering. The coveringmay assist in grasping the tissue and may later provide a surface fortissue ingrowth. Ingrowth of the surrounding tissues, such as the valveleaflets, provides stability to the device 14 as it is further anchoredin place and may cover the device with native tissue thus reducing thepossibility of immunologic reactions. The covering may be comprised ofany biocompatible material, such as polyethylene terepthalate,polyester, cotton, polyurethane, expanded polytetrafluoroethylene(ePTFE), silicon, or various polymers or fibers and have any suitableform, such as a fabric, mesh, textured weave, felt, looped or porousstructure. Generally, the covering has a low profile so as not tointerfere with delivery through an introducer sheath or with graspingand coapting of leaflets or tissue.

FIGS. 17A-17C illustrate a covering 100 on the fixation device 14wherein the device 14 is in various positions. FIG. 17A shows thecovering 100 encapsulating the distal elements 18 and the actuationmechanism 58 while the device 14 is in the open position. Thus, theengagement surfaces 50 are covered by the covering 100 which helps tominimize trauma on tissues and provides additional friction to assist ingrasping and retaining tissues. FIG. 17B shows the device 14 of FIG. 17Ain the inverted position. The covering 100 is loosely fitted and/or isflexible or elastic such that the device 14 can freely move to variouspositions and the covering 100 conforms to the contours of the device 14and remains securely attached in all positions. FIG. 17C shows thedevice 14 in the closed position. Thus, when the fixation device 14 isleft behind as an implant in the closed position, the exposed surfacesof the device 14 are substantially covered by the covering 100. It maybe appreciated that the covering 100 may cover specific parts of thefixation device 14 while leaving other parts exposed. For example, thecovering 100 may comprise sleeves that fit over the distal elements 18and not the actuation mechanism 58, caps that fit over the distal ends54 of the distal elements 18 or pads that cover the engagement surfaces50, to name a few. It may be appreciated that, the covering 100 mayallow any frictional accessories, such as barbs, to be exposed. Also,the covering 100 may cover the proximal elements 16 and/or any othersurfaces of the fixation device 14. In any case, the covering 100 shouldbe durable to withstand multiple introduction cycles and, when implantedwithin a heart, a lifetime of cardiac cycles.

The covering 100 may alternatively be comprised of a polymer or othersuitable materials dipped, sprayed, coated or otherwise adhered to thesurfaces of the fixation device 14. Optionally, the polymer coating mayinclude pores or contours to assist in grasping the tissue and/or topromote tissue ingrowth.

Any of the coverings 100 may optionally include drugs, antibiotics,anti-thrombosis agents, or anti-platelet agents such as heparin,COUMADIN® (Warfarin Sodium), to name a few. These agents may, forexample, be impregnated in or coated on the coverings 100. These agentsmay then be delivered to the grasped tissues surrounding tissues and/orbloodstream for therapeutic effects.

C. Fixation Device Locking Mechanisms

As mentioned previously, the fixation device 14 optionally includes alocking mechanism for locking the device 14 in a particular position,such as an open, closed or inverted position or any positiontherebetween. It may be appreciated that the locking mechanism includesan unlocking mechanism which allows the device to be both locked andunlocked. FIGS. 18-21 illustrate an embodiment of a locking mechanism106. Referring to FIG. 18, in this embodiment, the locking mechanism 106is disposed between the coupling member 19 and the base 69 of theactuation mechanism 58. The base 69 is fixedly attached to the stud 74which extends through the locking mechanism 106. The stud 74 isreleasably attached to the actuator rod 64 which passes through thecoupling member 19 and the shaft 12 of the interventional tool 10. Thebase 69 is also connected to the legs 68 of the actuation mechanism 58which are in turn connected to the distal elements 18.

FIG. 18 also illustrates the proximal elements 16, which in thisembodiment straddle the locking mechanism and join beneath the lockingmechanism 106. The proximal elements 16 are shown supported by proximalelement lines 90. The proximal elements 16 are raised and lowered bymanipulation of the proximal element lines 90. In addition, lock lines92 are shown connected with a release harness 108 of the lockingmechanism 106. The lock lines 92 are used to lock and unlock the lockingmechanism 106 as will be described below. The proximal element lines 90and lock lines 92 may be comprised of any suitable material, typicallywire, nitinol wire, cable, suture or thread, to name a few. In addition,the proximal element lines 90 and/or lock lines 92 may include acoating, such as parylene. Parylene is a vapor deposited pinhole freeprotective film which is conformal and biocompatible. It is inert andprotects against moisture, chemicals, and electrical charge.

FIG. 19 provides a front view of the locking mechanism 106 of FIG. 18.However, here the proximal elements 16 are supported by a singleproximal element line 90 which is through both of the proximal elements16. In this arrangement both of the elements are raised and loweredsimultaneously by action of a single proximal element line 90. Whetherthe proximal elements 16 are manipulated individually by separateproximal element lines 90 or jointly by a single proximal element line90, the proximal element lines 90 may extend directly through openingsin the proximal elements and/or through a layer or portion of a covering100 on the proximal elements, or through a suture loop above or below acovering 100.

FIGS. 20-21 illustrate the locking mechanism 106 showing the lockingmechanism 106 in the unlocked and locked positions respectively.Referring to FIG. 20, the locking mechanism 106 includes one or morewedging elements, such as rolling elements. In this embodiment, therolling elements comprise a pair of barbells 110 disposed on oppositesides of the stud 74, each barbell having a pair of generallycylindrical caps and a shaft therebetween. The barbells 110 and the stud74 are preferably comprised of cobalt chromium or stainless steel,however any suitable material may be used. The barbells 110 aremanipulated by hooked ends 112 of the release harness 108. When anupwards force is applied to the harness 108 by the lock line 92(illustrated in FIG. 18), the hooked ends 112 raise the barbells 110against a spring 114, as shown in FIG. 20. This draws the barbells 110up along a sidewall or sloping surface 116 which unwedges the barbells110 from against the stud 74. In this position, the stud 74 is free tomove. Thus, when the lock line 92 raises or lifts the harness 108, thelocking mechanism 106 is in an unlocked position wherein the stud 74 isfree to move the actuation mechanism 58 and therefore the distalelements 18 to any desired position. Release of the harness 108 by thelock line 92 transitions the locking mechanism 106 to a locked position,illustrated in FIG. 21. By releasing the upwards force on the barbells110 by the hooked ends 112, the spring 114 forces the barbells 110downwards and wedges the barbells 110 between the sloping surface 116and the stud 74. This restricts motion of the stud 74, which in turnlocks the actuation mechanism 58 and therefore distal elements 18 inplace. In addition, the stud 74 may include one or more grooves 82 orindentations which receive the barbells 110. This may provide more rapidand positive locking by causing the barbells 110 to settle in a definiteposition, increase the stability of the locking feature by furtherpreventing movement of the barbells 110, as well as tangible indicationto the user that the barbell has reached a locking position. Inaddition, the grooves 82 may be used to indicate the relative positionof the distal elements 18, particularly the distance between the distalelements 18. For example, each groove 82 may be positioned to correspondwith a 0.5 or 1.0 mm decrease in distance between the distal elements18. As the stud 74 is moved, the barbells 110 will contact the grooves82; by counting the number of grooves 82 that are felt as the stud 74 ismoved, the user can determine the distance between the distal elements18 and can provide the desired degree of coaptation based upon leafletthickness, geometry, spacing, blood flow dynamics and other factors.Thus, the grooves 82 may provide tactile feedback to the user.

The locking mechanism 106 allows the fixation device 14 to remain in anunlocked position when attached to the interventional tool 10 duringgrasping and repositioning and then maintain a locked position when leftbehind as an implant. It may be appreciated, however, that the lockingmechanism 106 may be repeatedly locked and unlocked throughout theplacement of the fixation device 14 if desired. Once the final placementis determined, the lock line 92 and proximal element lines 90 areremoved and the fixation device is left behind.

FIGS. 23, 24A-24B illustrate another embodiment of a locking mechanism106. Referring to FIG. 23, in this embodiment, the locking mechanism 106is again disposed between the coupling member 19 and the base 69 of theactuation mechanism 58. The base 69 is connected to the stud 74 whichextends through the locking mechanism 106, and connects to an actuatorrod which extends through the coupling member 19 and the shaft 12 of theinterventional tool 10. The base 69 is also connected to the legs 68 ofthe actuation mechanism 58 which are in turn connected to the distalelements 18. FIG. 23 also illustrates the proximal elements 16 whichmanipulate the locking mechanism 106 in this embodiment. The lockingmechanism 106 comprises folded leaf structures 124 having overlappingportions 124 a, 124 b, each folded structure 124 being attached to aproximal element 16. In FIG. 23 and FIG. 24A, the folded structures 124are shown without the remainder of the locking mechanism 106 forclarity. Proximal elements 16 are flexible and resilient and are biasedoutwardly. The folded leaf structures 124 include holes 125 (FIG. 24B)in each overlapping portion 124 a, 124 b so that the stud 74 passesthrough the holes 125 of the portions 124 a, 124 b as shown. The lockingmechanism includes slots into which ends 123 of the folded leafstructures 124 are fixed. When the proximal elements 16 are in anundeployed position, as in FIG. 23, the folded leaf structures 124 liesubstantially perpendicular to the stud 74 so that the holes 125 in eachoverlapping portion are vertically aligned. This allows the stud 74 topass freely through the holes and the locking mechanism 106 isconsidered to be in an unlocked position.

Deployment of the proximal elements 16, as shown in FIG. 24A, tilts thefolded leaf structures 124 so as to be disposed in a non-perpendicularorientation relative to the stud 74 and the holes 125 are no longervertically aligned with one another. In this arrangement, the stud 74 isnot free to move due to friction against the holes of the folded leafstructure 124. FIG. 24B provides a larger perspective view of the foldedstructures 124 in this position. Thus, the locking mechanism 106 isconsidered to be in a locked position. This arrangement allows thefixation device 14 to maintain an unlocked position during grasping andrepositioning and then maintain a locked position when the proximalelements 16 are deployed and the fixation device 14 is left behind as animplant. It may be appreciated, however, that the locking mechanism 106may be repeatedly locked and unlocked throughout the placement of thefixation device 14 if desired.

FIGS. 25, 26A-26B illustrate another embodiment of a locking mechanism106. Referring to FIG. 25, in this embodiment, the locking mechanism 106is again disposed between the coupling member 19 and the base 69 of theactuation mechanism 58. And, the base 69 is connected to the stud 74which extends through the locking mechanism 106 and connects to anactuator rod which extends through the coupling member 19 and the shaftof the interventional tool 10. FIG. 25 illustrates the proximal elements16 which manipulate the locking mechanism 106 in this embodiment. Thelocking mechanism 106 comprises C-shaped structures 128, each C-shapedstructure 128 attached to a proximal element 16. The C-shaped structures128 hook around the stud 74 so that the stud 74 passes through the “C”of each structure 128 as shown in FIGS. 26A-26B. As shown, thestructures 128 cross each other and the “C” of each structure 128 faceseach other. A spring 130 biases the C-shaped structures into engagementwith one another. When the proximal elements are in an undeployedposition, as in FIG. 26A, the C-shaped structures 128 are urged into anorientation more orthogonal to the axial direction defined by stud 74,thus bringing the “C” of each structure 128 into closer axial alignment.This allows the stud 74 to pass freely through the “C” of each structure128. Deployment of the proximal elements 16 outwardly urges the C-shapedstructures into a more angular, non-orthogonal orientation relative tostud 74 causing the sidewalls of the “C” of each structure 128 to engagestud 74 more forcefully. In this arrangement, the stud 74 is not free tomove due to friction against the “C” shaped structures 128.

D. Additional Embodiments of Fixation Devices

FIGS. 22A-22B illustrate a variation of the fixation device 14 describedabove in which the distal and proximal elements 16, 18 on each side ofthe fixation device are movable laterally toward and away from eachother to facilitate capture of more widely-separated leaflets or othertissue flaps. The coupling member 19 is bifurcated into two resilientand flexible branches 19A, 19B which are biased outwardly into theposition shown in FIG. 22A, but which are movable to the position shownin FIG. 22B. As an alternative, branches 19A, 19B may be more rigidmembers connected to coupling member 19 by pins or hinges so as to bepivotable toward and away from each other. Each of proximal elements 16and distal elements 18 are coupled at their proximal ends to one branch19A or 19B of the coupling member 19. Legs 68 are coupled at theirproximal ends to base 69, and therefore stud 74, and at their distalends to distal elements 18, as described above. Translation of stud 74distally or proximally relative to coupling member 19 opens or closesdistal elements 18 as in formerly described embodiments. A collar 131 isslidably disposed over coupling member 19 and has an annular groove 133on its inner wall configured to slide over and frictionally engagedetents 135 on branches 19A, 19B. A sheath 137 is positioned coaxiallyover shaft 12 and is slidable relative thereto to facilitate pushingcollar 131 distally over coupling member 19.

In use, the embodiment of FIGS. 22A-22B is introduced with distal andproximal elements 16, 18 in the closed position. Collar 131 is pusheddistally against, but not over, detents 135 so that branches 19A, 19Bare disposed together and fixation device 14 has a minimal profile. Whenthe user is ready to capture the target tissue (e.g. valve leaflets),sheath 137 is retracted so that collar 131 slides proximally overcoupling member 19. This allows branches 19A, 19B to separate into theposition of FIG. 22A. Actuator 64 is pushed distally so as to opendistal elements 18. Tension is maintained on proximal element lines 90(not shown in FIGS. 22A-22B) so that proximal elements 16 remainseparated from distal elements 18. When tissue is positioned between theproximal and distal elements, tension is released on proximal elementlines 90 allowing the tissue to be captured between the proximal anddistal elements. Sheath 137 may then be advanced distally so that collar131 urges branches 19A, 19B back together. Sheath 137 is advanced untilgroove 133 in collar 131 slides over detents 135 and is frictionallymaintained thereon as shown in FIG. 22B. Sheath 137 may then beretracted from collar 131. Distal elements 18 may be closed, opened orinverted by advancing or retracting stud 74 via actuator 64, as in theembodiments described above. It should be understood that the embodimentof FIGS. 22A-22B preferably includes a locking mechanism as describedabove, which has been omitted from the figures for clarity.

In a further alternative of the embodiment of FIGS. 22A-22B, fixationdevice 14 may be configured to allow for independent actuation of eachof the lateral branches 19A,19B and/or distal elements 18. In anexemplary embodiment, shaft 12 and coupling member 19 may belongitudinally split into two identical halves such that a first branch19A may be drawn into collar 131 independently of a second branch 19B.Similarly, actuator shaft 64 may be longitudinally split so that eachhalf can slide independently of the other half, thus allowing one ofdistal elements 18 to be closed independently of the other distalelement 18. This configuration permits the user to capture one of thevalve leaflets between one of the distal and proximal elements 16, 18,then draw the corresponding branch 19A into the collar 131. The fixationdevice 14 may then be repositioned to capture a second of the valveleaflets between the other proximal and distal elements 16, 18, afterwhich the second branch 19B may be drawn into collar 131 to complete thecoaptation. Of course, the closure of distal elements 18 may occureither before or after branches 19A, 19B are drawn into collar 131.

FIGS. 27-28 illustrate an additional embodiment of the fixation device14. As shown in FIG. 27, the fixation device 14 includes a couplingmember 19 which couples the device 14 to the shaft 12 of theinterventional tool 10. Here, the device 14 also includes a top coupler150 attached to coupling member 19 and a bottom coupler 152 attached tothe stud 74 so that the two couplers are axially moveable relative toone another. The distal elements 18 are rotatably attached to the topcoupler 150 by upper pins 156 and rotatably attached to the bottomcoupler 152 by lower pins 160. When the bottom coupler 152 is advanced,the pins 156, 160 are drawn apart. The upper pins 156 are disposedwithin slots 158 as shown. When the bottom coupler 152 is advanceddistally relative to top coupler 150, pins 156, 160 are drawn apart.Angling of the slots 158 causes the distal elements 18 to rotate towardthe coupling member 19 as the pins 156, 160 are drawn apart. Relativemovement of the couplers 150, 152 may be achieved by any suitablemechanism including sliding or threading.

FIG. 28 illustrates the fixation device 14 in the closed position. Here,the device 14 has a low profile (width in the range of approximately0.140-0.160 inches orthogonal to the axial direction defined by shaft12/stud 74) so that the device 14 may be easily passed through acatheter and through any tissue structures. To open the device 14 thebottom coupler 152 is then retracted or the couplers 150, 152 broughttoward one another to rotate the distal elements 18 outward. Thecomponents of the fixation device 14 may be formed from stainless steelor other suitable metal, such as by machining, or formed from a polymer,such as by injection molding. In addition, portions of the fixationdevice 14, particularly the distal elements 18, may be covered with acovering such as described above, to promote tissue ingrowth, reducetrauma, enhance friction and/or release pharmacological agents.Alternatively, the device 14 may have a smooth surface which preventscellular adhesion thereby reducing the accumulation of cells havingpotential to form an emboli.

Optionally, the fixation device 14 may include tissue retention featuressuch as barbs 170 and/or bumpers 172, illustrated in FIGS. 29-30. Thebarbs 170 may extend from the engagement surfaces 50 of the distalelements 18, as shown, and may be present in any number and anyarrangement. Thus, the barbs 170 will engage the leaflets or tissueduring grasping to assist in holding the tissue either by frictionalengagement, minor surface penetration or by complete piercing of thetissue, depending on the length and shape of the barbs 170 selected.Alternatively or in addition, bumpers 172 may extend from the distalelements 18. As shown in FIG. 29, each bumpers 172 may extend from theproximal end 52 of the distal element 18 and curve toward the free end54 of the distal element 18. Or, as shown in FIG. 30, each bumper 172may extend from the free end 54 and curve toward the proximal end 52.Bumpers 172 are preferably constructed of a resilient metal or polymerand may have any of various geometries, including a solid thin sheet ora loop-shaped wire form. The bumpers 172 may help to actively engage anddisengage tissue from the barbs 170 during opening and closing of thefixation device 14. Further, to assist in grasping a tissue, theengagement surfaces 50 may have any texture or form to increase frictionagainst the grasped tissue. For example, the surfaces 50 may includeserrations, scales, felt, barbs, polymeric frictional elements, knurlingor grooves, to name a few.

FIG. 31 illustrates the engagement surface 50 having a serrated edge 174to improve grip on tissue engaged. FIG. 31 also illustrates anembodiment of the fixation device 14 mounted on an interventional tool10 or delivery catheter for ventricular approach to the mitral valve.Here the device 14 is mounted on the shaft 12 with the engagementsurfaces 50 facing distally relative to shaft 12 (and facing upstreamrelative to the mitral valve). Thus, when the mitral valve is approachedfrom the ventricular side, the engagement surfaces 50 can be pressedagainst the downstream surfaces of the valve without passing through thevalve. It may be appreciated that any of the embodiments of the fixationdevice 14 described herein may be mounted on shaft 12 in thisorientation for approach to any valve or tissue, including embodimentsthat include both proximal and distal elements.

It may be appreciated that when the fixation device 14 is mounted on theshaft 12 in orientation illustrated in FIG. 31, the position of thedistal elements and the proximal elements are reversed. In suchinstances it is useful to keep in mind that the distal elements contactthe distal surface or downstream surface of the leaflets and theproximal elements contact the proximal surface or upstream surface ofthe leaflets. Thus, regardless of the approach to the valve and therelative position of the proximal and distal elements on the fixationdevice, the proximal and distal elements remain consistent in relationto the valve.

FIGS. 32-34 illustrate an additional embodiment of the fixation device14. As shown in FIG. 32, the fixation device 14 includes a couplingmember 19, proximal elements 16 and distal elements 18 which are eachconnected to a set of base components 186. The distal elements 18 areconnected to the base components 186 (top base component 186 a and abottom base component 186 b) by extension arms 188. In this embodiment,each distal element 18 is connected by two extension arms 188 in acrossed arrangement so that one extension arm 188 connects the distalelement 18 to the top base component 186 a and the other extension arm188′ connects the distal element 18 to the bottom base component 186 b.The top base component 186 a can be separated from the bottom basecomponent 186 b by any suitable method which may be torque driven,spring driven or push/pull. Increasing the separation distance betweenthe base components 186 draws the distal elements 18 inwards toward thebase components 186, as shown in FIG. 33. This allows the tissue to begrasped between the distal elements 18 and proximal elements 16 while inan arrangement wherein the distal elements 18 are parallel to eachother. This may prevent inconsistent compression of the tissue and maybetter accommodate tissues or leaflets of varying thicknesses. As shownin FIG. 34, the distal elements 18 may be drawn together and theproximal elements 16 may be retracted to form a low profile fixationdevice 14.

FIGS. 35-39, 40A-40D, 41-42, 43A-43C illustrate another embodiment ofthe fixation device 14. In this embodiment, the device 14 is deliverablein the inverted position and moveable to the open position for graspingof the tissue. FIG. 35 illustrates the fixation device 14 in theinverted position. The fixation device 14 includes a shaft 198, proximalelements 16 and distal elements 18. Each distal element 18 has aproximal end 52 rotatably connected to the shaft 198 and a free end 54.The fixation device 14 also includes an actuator rod 204, a base 202 anda pair of deployment arms 200 attached to the base 202 as shown. In theinverted position, the extender 204 is extended and deployment arms 200are disposed between the actuator rod 204 and the distal elements 18. Asshown in FIG. 36, the actuator rod 204 may be retracted so that thedeployment arms 200 press against the distal elements 18, rotating thedistal elements 18 from the inverted position to the open position. Theangle of the distal elements 18 may be adjusted by retracting orextending the actuator rod 204 various distances. As shown in FIG. 37,further retraction of the actuator rod 204 raises the distal elements 18further.

In the open position, tissue or leaflets may be grasped between thedistal elements 18 and proximal elements 16. FIG. 38 illustrates theproximal elements 16 in their released position wherein the tissue orleaflet would be present therebetween. Hereinafter, the tissue will bereferred to as leaflets. In this embodiment, each distal element 18includes an implant pledget 210, typically press-fit or nested withineach distal element 18. The implant pledgets 210 will be attached to theleaflets by ties, such as sutures or wires, and will be used to hold theleaflets in desired coaptation. The implant pledgets 210 will then beseparated from the fixation device 14 and will remain as an implant.

To attach the implant pledgets 210 to the leaflets, the leaflets andimplant pledgets 210 are punctured by fixation tools 220, as shown inFIG. 39. The fixation tools 220 extend from the catheter 86, passthrough the leaflets and puncture the implant pledgets 210. Thus, thepledgets 210 are comprised of a puncturable material, such as structuralmesh. The fixation tools 220 are used to deliver an anchor 222 asillustrated in larger view in FIGS. 40A-40D. FIG. 40A shows the fixationtool 220 including a sleeve 224 surrounding the fixation tool 220 and ananchor 222 loaded therebetween. In this embodiment, the anchor includesone or more flaps 228 which are held within the sleeve 224. It may beappreciated that the anchor 222 may have any suitable form. Additionalexemplary embodiments of anchors are provided in commonly assigned U.S.Pat. No. 6,752,813 incorporated herein for all purposes. A suture 226 isattached to the anchor 222 and extends through the sleeve 224 or on theoutside of the sleeve 224, as shown, to the catheter 86. The fixationtools 220 are advanced so that the anchor 222 passes through the leaflet(not shown) and the pledget 210, as shown in FIG. 41.

Referring now to FIG. 40B, the sleeve 224 is then retracted to exposethe flaps 228 which releases the anchor 222 from the confines of thesleeve 224. The flaps 228 extend radially outwardly, illustrated in FIG.40C, by spring loading, shape memory or other self-expanding mechanism.Thus, the flaps 228 are positioned against the distal side of thepledget 210, the suture 226 passing through the pledget 210 and theleaflet, as shown in FIG. 41. At this point, the pledgets 210 can beremoved from the distal elements 18. By extending the actuator rod 204distally, the base 202 draws the deployment arms 200 distally whichreturns the distal elements 18 to the inverted position, as shown inFIG. 42. Since the pledgets 210 have been pierced by the fixation tools220 and the anchors 222 have been deployed, the pledgets 210 and theleaflets disengage from distal elements 18 and remain in position. Theproximal elements 16 may also be returned to their initial position asshown, using any of various mechanisms as have been described above inconnection with other embodiments. Referring now to FIG. 40D, thefixation tool 220 is then removed while the anchor 222 remains in placewith suture 226 attached.

The implant pledgets 210 are then separated from the fixation device 14and left behind to maintain coaptation of the leaflets in the desiredposition. FIGS. 43A-43C illustrate the implant pledgets 210 from variousperspective views. FIG. 43A provides a perspective top view showing thatthe pledgets 210 are connected by a link 230 that allows the pledgets210 to be released from one side of the fixation device 14. In addition,the sutures 226 are fixed together, either by knot tying or placement ofa suture fastener 232 as shown. It may be appreciated that the suturefastener 232 may have any suitable form. Additional exemplaryembodiments of suture fasteners 232 are provided in commonly-assignedU.S. Pat. No. 7,048,754, which is incorporated herein by reference forall purposes. FIG. 43B provides a perspective bottom view showing theanchor 222 positioned against the bottom side of the pledget 210.Likewise, FIG. 43C provides a perspective side view also showing theanchor 222 positioned against the bottom side of the pledget 210.

FIGS. 44A-44B, 45-46 illustrate another embodiment of the fixationdevice 14. As shown in FIG. 44A, the fixation device 14 is mounted onthe shaft 12 and is comprised of distal elements 18 and a retention clip36 comprised of a semi-rigid material having a folded shape. Thematerial may be any suitable material providing rigidity with recoilingproperties such as various metals or plastics. The folded shape is suchthat a fold 252 is directed distally and free ends 254 are directedproximally toward the distal elements 18. Penetration elements 256 aredisposed near the free ends 254 and directed toward the shaft 12. Inaddition, an opening 258 is located near the fold 252, as illustrated inFIG. 44B which provides a perspectives view of the device 14. Referringback to FIG. 44A, the fold 252 is attached to an actuator rod 74 whichpasses through the shaft 12 and an arrow-shaped structure 260 isdisposed on the shaft 12 between the free ends 254, proximal to theopening 258, as shown. In this arrangement, the fixation device 14 isadvanced through the valve so that the distal elements 18 are disposedbelow the leaflets. The device may then be retracted proximally tocapture the leaflets within the distal elements 18. As shown in FIG. 45,retraction of the actuator rod 74 draws the retention clip 36 toward thedistal elements 18 so that the sloping sides of the arrow-shapedstructure 260 force the free ends 254 outward, away from the shaft 12.Further retraction of actuator rod 74 results in the sloping sides ofarrow shaped structure 260 falling into the opening 258 in retentionclip 36, causing retention clip 36 to recoil back to the closed positionas shown in FIG. 46, with the free ends 254 extending through the distalelements 18. This allows the penetration elements 256 to penetrate theleaflets (not shown) to secure engagement therewith. The actuator rod 74is then detached from the retention clip 36 and shaft 12 is detachedfrom distal elements 18 which are left in place to hold the leaflets ina coapted arrangement.

It may be appreciated that the foregoing embodiment may also includeproximal elements 16 configured to be positioned on the upstream side ofthe valve leaflets to assist in the capture and fixation. Such proximalelements may be mounted to shaft 12 so as to be removed followingfixation of the leaflets, or the proximal elements may be connected todistal elements 18 and/or retention clip 36 to be implanted therewith.

In further embodiments, the proximal elements may be manipulated toenhance gripping. For example, the proximal elements may be lowered tograsp leaflets or tissue between the proximal and distal elements, andthen the proximal elements may be moved to drag the leaflets or tissueinto the fixation device. In another example, the proximal elements maybe independently lowered to grasp the leaflets or tissue. This may beuseful for sequential grasping. In sequential grasping, one proximalelement is lowered to capture a leaflet or tissue portion between theproximal and distal elements. The fixation device is then moved,adjusted or maneuvered to a position for grasping another leaflet ortissue portion between another set of proximal and distal elements. Inthis position, the second proximal element is then lowered to grasp thisother leaflet or tissue portion.

IV. Delivery Device

A. Overview of Delivery Device

FIG. 47 provides a perspective view of an embodiment of a deliverydevice or delivery catheter 300 which may be used to introduce andposition a fixation device as described above. The delivery catheter 300includes a shaft 302, having a proximal end 322 and a distal end 324,and a handle 304 attached to the proximal end 322. A fixation device(not shown) is removably coupleable to the distal end 324 for deliveryto a site within the body, typically for endovascular delivery to themitral valve. Thus, extending from the distal end 324 is a couplingstructure 320 for coupling with a fixation device. Also extending fromthe distal end 324 is an actuator rod 64. The actuator rod 64 isconnectable with the fixation device and acts to manipulate the fixationdevice, typically opening and closing the distal elements. Such couplingto a fixation device is illustrated in FIG. 48.

FIG. 48 illustrates an embodiment of a fixation device 14 coupled to thedistal end 324 of the delivery catheter 300. The shaft 302 is shownhaving a nose 318 near its distal end 324. In this embodiment, the nose318 has a flanged shape. Such a flanged shape prevents the nose 318 frombeing retracted into a guiding catheter or introducer as will bediscussed in later sections. However, it may be appreciated that thenose 318 may have any shape including bullet, rounded, blunt or pointed,to name a few. Extending from the nose 318 is a compression coil 326through which the coupling structure 320 and actuator rod 64 pass. Theactuator rod 64 is coupleable, as shown, with the stud 74 of thefixation device 14. Such coupling is illustrated in FIG. 49.

FIG. 49 illustrates a portion of the shaft 302 of the delivery catheter300 and a fixation device 14 which is coupleable with the catheter 300.Passing through the shaft 302 is the actuator rod 64. In thisembodiment, the actuator rod 64 comprises a proximal extremity 303 and adistal extremity 328, the distal extremity 328 of which is surrounded bya coil 330. The proximal extremity 303 is typically comprised ofstainless steel, nitinol, or Elgiloy®, to name a few, and may have adiameter in the range of 0.010 in. to 0.040 in., preferably 0.020 in. to0.030 in., more preferably 0.025 in., and a length in the range of 48 to72 in. The distal extremity 328 may be tapered, is typically comprisedof stainless steel, nitinol, or Elgiloy®, to name a few, and may have adiameter in the range of 0.011 to 0.025 in and a length in the range of4 to 12 in. Such narrowing increases flexibility of the distal end 324of the actuator rod 64. The actuator rod 64 further comprises a joiner332 which is attached to the distal extremity 328. The joiner 332 isremovably attachable with stud 74 of the fixation device 14. In thisembodiment, the joiner 332 has internal threads which mate with externalthreads on the stud 74 of the fixation device 14. As describedpreviously, the stud 74 is connected with the distal elements 18 so thatadvancement and retraction of the stud 74, by means of the actuator rod64, manipulates the distal elements. Likewise, the coupling member 19 ofthe fixation device 14 mates with the coupling structure 320 of thecatheter 300. Thus, the coupling member 19 and coupling structure 320function as previously described in relation to FIGS. 6A-6B.

Referring back to FIG. 48, the fixation device 14 may also include alocking mechanism which includes a release harness 108, as previouslydescribed in relation to FIGS. 18-21. Lock lines 92 are connected withthe release harness 108 to lock and unlock the locking mechanism 106 aspreviously described. The lock lines 92 extend through the shaft 302 ofthe delivery catheter 300 and may connect with the release harness 108in various arrangements as will be illustrated in later sections.Similarly, proximal element lines 90 extend through the shaft 302 of thedelivery catheter 300 and connect with the proximal elements 16. Theproximal elements 16 are raised and lowered by manipulation of theproximal element lines 90 as previously described. The proximal elementlines 90 may connect with the proximal elements 16 in variousarrangements as will be illustrated in later sections.

Referring back to FIG. 47, the handle 304 attached to the proximal end322 of the shaft 302 is used to manipulate the coupled fixation device14 and to optionally decouple the fixation device 14 for permanentimplantation. As described, the fixation device 14 is primarilymanipulated by the actuator rod 64, proximal element lines 90 and locklines 92. The actuator rod 64 manipulates the distal elements 18, theproximal element lines 90 manipulate the proximal elements 16 and thelock lines 92 manipulate the locking mechanism. In this embodiment, theactuator rod 64 may be translated (extended or retracted) to manipulatethe distal elements 18. This is achieved with the use of the actuatorrod control 314 which will be described in later sections. The actuatorrod 64 may also be rotated to engage or disengage the threaded joinerwith the threaded stud 74. This is achieved with the use of the actuatorrod handle 316 which will also be described in later sections. Further,the proximal element lines 90 may be extended, retracted, loaded withvarious amounts of tension or removed with the use of the proximalelement line handle 312. And, the lock lines 92 may be may be extended,retracted, loaded with various amounts of tension or removed with theuse of the lock line handle 310. Both of these handles 310, 312 will bedescribed in more detail in later sections. The actuator rod handle 316,actuator rod control 314, proximal element line handle 312 and lock linehandle 310 are all joined with a main body 308 within which the actuatorrod 64, proximal element lines 90 and lock lines 92 are guided into theshaft 302. The handle 304 further includes a support base 306 connectedwith the main body 308. The main body 308 is slideable along the supportbase 306 to provide translation of the shaft 302. Further, the main body308 is rotatable around the support base 306 to rotate the shaft.

B. Delivery Catheter Shaft

FIG. 50 illustrates a cross-sectional view of the delivery cathetershaft 302 of FIG. 47. In this embodiment, the shaft 302 has a tubularshape with inner lumen 348 and is comprised of a material which provideshoop strength while maintaining flexibility and kink resistance, such asa braided laminated material. Such material may include stainless steelbraided or coiled wire embedded in a polymer such as polyurethane,polyester, Pebax, Grilamid TR55, and AESNO to name a few. To providefurther support and hoop strength, a support coil 346 is disposed withinthe lumen 348 of shaft 302 as illustrated in FIG. 50.

Passing through the support coil 346 are a variety of elongated bodies,including tubular guides and cylindrical rods. For example, one type oftubular guide is a compression coil 326 extending through lumen 348 fromthe proximal end 322 to the distal end 324 of the shaft 302, and theactuator rod 64 extends through the compression coil 326. Therefore, thecompression coil typically has a length in the range of 48 to 60 in. andan inner diameter in the range of 0.020 to 0.035 in. to allow passage ofthe actuator rod 64 therethrough. The actuator rod 64 is manipulable torotate and translate within and relative to the compression coil 326.The compression coil 326 allows lateral flexibility of the actuator rod64 and therefore the shaft 302 while resisting buckling and providingcolumn strength under compression. The compression coil may be comprisedof 304V stainless steel to provide these properties.

To provide additional tensile strength for the shaft 302 and to minimizeelongation, a tension cable 344 may also pass through the support coil346. The tension cable 344 extends through lumen 348 from the proximalend 322 to the distal end 324 of the shaft 302. Therefore, the tensioncable 344 typically has a diameter in the range of 0.005 in. to 0.010in. and a length in the range of 48 to 60 in. In preferred embodiments,the tension cable 344 is comprised of 304V stainless steel.

In addition, at least one lock line shaft 341 having a tubular shape maybe present having a lock line lumen 340 through which lock lines 92 passbetween the lock line handle 310 and the locking mechanism 106. The lockline shaft 341 extends through lumen 348 from the proximal end 322 tothe distal end 324 of the shaft 302. Therefore, the lock line shaft 341typically has a length in the range of 48 to 60 in., an inner diameterin the range of 0.016 to 0.030 in., and an outer diameter in the rangeof 0.018 to 0.034 in. In preferred embodiments, the lock line shaft 341is comprised of a 304V stainless steel coil however other structures ormaterials may be used which provide kink resistance and compressionstrength.

Similarly, at least one proximal element line shaft 343 having a tubularshape may be present having a proximal element line lumen 342. Proximalelement lines 90 pass through this lumen 342 between the proximalelement line handle 312 and the proximal elements 16. Thus, the proximalelement line shaft 343 extends through lumen 348 from the proximal end322 to the distal end 324 of the shaft 302. Therefore, the proximalelement line shaft 343 typically has a length in the range of 48 to 60in., an inner diameter in the range of 0.016 to 0.030 in., and an outerdiameter in the range of 0.018 to 0.034 in. In preferred embodiments,the proximal element line shaft 343 is comprised of a 304V stainlesssteel coil however other structures or materials may be used whichprovide kink resistance and compression strength.

In this embodiment, the elongated bodies (compression coil 326 enclosedactuator rod 64, tension cable 344, lock line shaft 342, proximalelement line shaft 343) each “float” freely in inner lumen 348 withinthe support coil 346 and are fixed only at the proximal end 322 anddistal end 324 of shaft 302. The lumen 348 is typically filled andflushed with heparinized saline during use. Alternatively or inaddition, the lumen 348 may be filled with one or more fillers, such asflexible rods, beads, extruded sections, gels or other fluids.Preferably the fillers allow for some lateral movement or deflection ofthe elongated bodies within lumen 348 but in some cases may restrictsuch movement. Typically, the elongated bodies are fixed at the proximaland distal ends of the shaft and are free to move laterally androtationally therebetween. Such freedom of movement of the elongatedbodies provides the shaft 302 with an increased flexibility as theelongated bodies self-adjust and reposition during bending and/ortorqueing of the shaft 302. It may be appreciated that the elongatedbodies may not be fixed at the proximal and distal ends. The elongatedbodies are simply unconstrained relative to the shaft 302 in at leastone location so as to be laterally moveable within the lumen 348.Preferably the elongated bodies are unrestrained in at least a distalportion of the catheter, e.g. 5-15 cm from the distal end 324, so as toprovide maximum flexibility in the distal portion.

It may be appreciated, however, that alternate shaft 302 designs mayalso be used. For example, referring to FIG. 51, in this embodiment theshaft 302 again has a tubular shape with an inner lumen 348 and asupport coil 346 disposed within the lumen 348 of shaft 302. Filling theinner lumen 348 within the support coil 346 is an extrusion 334 havinglumens through which pass a variety of elongated bodies, including thecompression coil 326 enclosed actuator rod 64, tension cable 344, lockline shafts 342, and proximal element line shafts 343, as shown. Thesupport coil 346 and elongated bodies may have the same geometries andbe comprised of the same materials as described above in relation toFIG. 50.

Alternatively, as shown in FIG. 52, the shaft 302 may include aninternal partition 350 to create multiple lumens within the shaft 302.For example, the partition 350 may have a central lumen 352 for passageof the actuator rod 64, optionally surrounded by the compression coil326. In addition, the partition 350 may also create at least one lockline lumen 340 for passage of a lock line 92 and at least one proximalelement line lumen 341 for passage of a proximal element line 90.Optionally, each of the lumens defined by partition 350 may be linedwith a kink-resistant element, such as a coil as in previousembodiments.

FIGS. 52A-52C illustrate embodiments of the nose 318 of the shaft 302.In FIG. 52A, the nose 318 comprises a tip ring 280 and a lock ring 282.In preferred embodiments, Epoxy and PEBAX are deposited between the tipring 280 and the lock ring 282 to bond them together. The lock ring 282has a geometry to mate with the tip ring 280 to maintain relativealignment between the two. FIG. 52B illustrates another embodiment ofthe nose 318 of the shaft 302. Here, the tip ring 280 is covered by asoft tip 284 to provide a more atraumatic tip and a smoother transitionto the shaft.

C. Lock Line Arrangements

As mentioned previously, when lock lines 92 are present, the lines 92pass through at least one lock line lumen 340 between the lock linehandle 310 and the locking mechanism 106. The lock lines 92 engage therelease harnesses 108 of the locking mechanism 106 to lock and unlockthe locking mechanism 106 as previously described. The lock lines 92 mayengage the release harnesses 108 in various arrangements, examples ofwhich are illustrated in FIGS. 53A-53C. In each embodiment, two lockline lumens 340 are present within the shaft 302 of the deliverycatheter 300 terminating at the nose 318. The lumens 340 are disposed onalternate sides of the actuator rod 64 so that each lumen 340 isdirected toward a release harness 108.

FIG. 53A illustrates an embodiment wherein two lock lines 92, 92′ passthrough a single lock line lumen 340 and are threaded through a releaseharness 108 on one side of the actuator rod 64 (the actuator rod 64 isshown without surrounding housing such as coupling structure, forclarity). The lock lines 92, 92′ are then separated so that each lockline passes on an opposite side of the actuator rod 64. The lock lines92, 92′ then pass through the release harness 108′ on the opposite sideof the actuator rod 64 and continue together passing through a anothersingle lock line lumen 340′. This lock line arrangement is the samearrangement illustrated in FIG. 48.

FIG. 53B illustrates an embodiment wherein one lock line 92 passesthrough a single lock line lumen 340, is threaded through a releaseharness 108 on one side of the actuator rod 64, and is returned to thelock line lumen 340. Similarly, another lock line 92′ passes throughanother single lock line lumen 340′, is threaded through a differentrelease harness 108′ located on the opposite side of the actuator rod64, and is returned to the another single lock line lumen 340′.

FIG. 53C illustrates an embodiment wherein both lock lines 92, 92′ passthrough a single lock line lumen 340. One lock line 92 is threadedthrough a release harness 108 on one side of the actuator rod 64 and isthen passed through another lock line lumen 340′ on the opposite side ofthe actuator rod 64. The other lock line 92′ is threaded through anotherrelease harness 108′ on the other side of the actuator rod 64′ and isthen passed through the another lock line lumen 340′ with the previouslock line 92.

It may be appreciated that a variety of lock line arrangements may beused and are not limited to the arrangements illustrated and describedabove. The various arrangements allow the harnesses 108 to bemanipulated independently or jointly, allow various amounts of tensionto be applied and vary the force required for removal of the lock lineswhen the fixation device is to be left behind. For example, a singlelock line passing through one or two lumens may be connected to bothrelease harnesses for simultaneous application of tension.

D. Proximal Element Line Arrangements

As mentioned previously, when proximal element lines 90 are present, thelines 90 pass through at least one proximal element line lumen 342between the proximal element line handle 312 and at least one proximalelement 16. The proximal element lines 90 engage the proximal elements16 to raise or lower the element 16 as previously described. Theproximal element lines 90 may engage the proximal elements 16 in variousarrangements, examples of which are illustrated in FIGS. 54A-54B. Ineach embodiment, two proximal element line lumens 342 are present withinthe shaft 302 of the delivery catheter 300 terminating at the nose 318.The lumens 342 are disposed on alternate sides of the actuator rod 64(the actuator rod 64 is shown without surrounding housing such ascoupling structure, for clarity) so that each lumen 342 is directedtoward a proximal element 16.

FIG. 54A illustrates an embodiment wherein one proximal element line 90passes through a single proximal element line lumen 342. The proximalelement line 90 is threaded through an eyelet 360 of a proximal element16 on one side of the actuator rod 64, passes over the actuator rod 64and is threaded through an eyelet 360′ of another proximal element 16′on the other side of the actuator rod 64. The proximal element line 90then passes through another single proximal element line lumen 342′.This proximal element line arrangement is the same arrangementillustrated in FIG. 48.

FIG. 54B illustrates an embodiment wherein one proximal element line 90passes through a single proximal element line lumen 342, is threadedthrough an eyelet 360 of a proximal element 16 on one side of theactuator rod 64, and is returned to the proximal element line lumen 342.Similarly, another proximal element line 90′ passes through anothersingle proximal element line lumen 342′ on the opposite side of theactuator rod 64, and is returned to the another single proximal elementline lumen 342′.

It may be appreciated that a variety of proximal element linearrangements may be used and are not limited to the arrangementsillustrated and described above. The various arrangements allow theproximal elements to be manipulated independently or jointly, allowvarious amounts of tension to be applied and vary the force required forremoval of the proximal element lines when the fixation device is to beleft behind. For example, a single proximal element line passing throughone or two lumens in shaft 302 may be used for simultaneous actuation ofboth proximal elements.

E. Main Body of Handle

FIG. 55 illustrates an embodiment of the handle 304 of the deliverycatheter 300. As mentioned previously, the actuator rod handle 316,actuator rod control 314, proximal element line handle 312 and lock linehandle 310 are all joined with the main body 318. The handle 304 furtherincludes a support base 306 connected with the main body 308. The mainbody 308 is slideable along the support base 306 to provide translationof the shaft 302 and the main body 308 is rotatable around the supportbase 306 to rotate the shaft.

FIG. 56 provides a partial cross-sectional view of the main body 308 ofthe handle 304 depicted in FIG. 55. As shown, the main body 308 includesa sealed chamber 370 within which the actuator rod 64, proximal elementlines 90 and lock lines 92 are guided into the shaft 302. The sealedchamber 370 is in fluid communication with the inner lumen 348 of shaft302 and is typically filled with saline and flushed with heparin orheparinized saline. The sealed chamber 370 has a seal 372 along itsperimeter to prevent leakage and the introduction of air to the chamber370. Any air in the chamber 370 may be bled from the chamber 370 by oneor more luers 374 which pass through the main body 308 into the chamber370 as illustrated in FIG. 55. In this embodiment, the handle 304includes two such luers 374, one on each side of the main body 308(second luer symmetrically positioned on backside of main body 308 inFIG. 55, hidden from view). Referring now to FIG. 56, the sealed chamber370 also has various additional seals, such as an actuator rod seal 376which surrounds the actuator rod 64 where the actuator rod 64 enters thesealed chamber 370, and a shaft seal 378 which surrounds the shaft 302where the shaft 302 enters the sealed chamber 370.

F. Lock Line Handle and Proximal Element Line Handle

As mentioned previously, the lock lines 92 may be may be extended,retracted, loaded with various amounts of tension or removed using thelock line handle 310. Likewise, the proximal element lines 90 may beextended, retracted, loaded with various amounts of tension or removedusing the proximal element line handle 312. Both of these handles 310,312 may be similarly designed to manipulate the appropriate lines 90, 92passing therethrough.

FIG. 57 illustrates an embodiment of a lock line handle 310 having locklines 92 passing therethrough. The lock line handle 310 has a distal end384, a proximal end 382 and an elongate shaft 383 therebetween. Thedistal end 382 is positionable within the sealed chamber 370 so that theproximal end 382 extends out of the chamber 370, beyond the main body308. The free ends of the lock lines 92 are disposed near the proximalend 382, passing through the wall of the handle 310 near a threaded nub390. The handle 310 further includes a cap 388 which is positionable onthe nub 309. Internal threading with the cap 388 mates with thethreading on the threaded nub 390 so that the cap 388 holds the freeends of the lock lines 92 between the cap 388 and the nub 390 and/orother portions of the handle 310 by friction. The lock lines 92 passthrough a central lumen (not shown) of the elongate shaft 383, extendthrough the sealed chamber 370 (as shown in FIG. 56) and extend throughthe shaft 302 to the locking mechanism 106.

Disposed near the distal end 384 of the handle 310 is at least one wing392. In the embodiment of FIG. 57, two wings 392 are present, each wing392 disposed on opposite sides of the elongate shaft 383. The wings 392extend radially outwardly and curve proximally so that a portion isparallel to the elongate shaft 383, as shown. It may be appreciated thatthe wings 392 may alternatively have the shape of solid or continuousprotrusions which extend radially and have a portion which is parallelto the elongate shaft 383. The wings 392 are used to hold the lock linehandle 310 in a desired position which in turn holds the lock under adesired load of tension, as will be described further below. The handle310 also includes a finger grip 386 near the proximal end 382 whichextends radially outwardly in alignment with the radial extension of theat least one wing 392. Thus, the user may determine the orientation ofthe wings 392 within the sealed chamber 370 from the orientation of thefinger grip 386 outside of the main body 308. The finger grip 386 mayalso serve an ergonomic purpose to assist in manipulating the handle310.

The portion of the wings 392 parallel to the elongate shaft 383 havegrooves or serrations 394. The serrations 394 are used to apply tensionto the lock lines 92. As shown in FIG. 57A, the lock line handle 310 ispositioned within a semi-tube 400 which is disposed within the sealedchamber 370. The semi-tube 400 comprises a top half 402 and a bottomhalf 404, each half 402, 404 having grooves or serrations 406 which matewith the serrations 394 of the wings 392. Thus, when the wings 392 arerotated to mate the serrations 394, 406, as shown in FIG. 58A, theelongate shaft 383 is held in place. Likewise, the wings 392 may berotated, as shown in FIG. 58B, so that the wings 392 are disposedbetween the halves 402, 404 and the serrations 394, 406 are disengaged.In this position, the shaft 383 may be translated to apply or releasetension in the lock lines 92. Thus, tension in the lines 92 may beadjusted by rotating the shaft 383 to disengage the serrations 394, 406,translating the shaft 383 and then rotating the shaft 383 back toreengage the serrations 394, 406. Alternatively, the finger grip 386 maybe pulled to apply tension to the lock lines 92. Pulling the finger grip386 translates the lock line handle 310 within the semi-tube 400. Suchtranslation is achievable due to angling of the serrations 394, 406 andflexibility of wings 382. However, the angling of the serrations 394,406 prevents translation in the opposite direction, i.e. by pushing thefinger grip 386. Therefore, to release tension from the lock lines 92,the shaft 383 is rotated to disengage the serrations 394, 406, allowingtranslation of the shaft 383, and then the shaft 383 is rotated back toreengage the serrations 394, 406.

To remove the lock lines 92, the cap 388 is removed from the threadednub 390 exposing the free ends of the lock lines 92. If one lock line 92is present having two free ends, continuous pulling on one of the freeends draws the entire length of lock line 92 out of the catheter 300. Ifmore than one lock line 92 is present, each lock line 92 will have twofree ends. Continuous pulling on one of the free ends of each lock line92 draws the entire length of each lock line 92 out of the catheter 300.

It may be appreciated that the proximal element line handle 312 hascorresponding features to the lock line handle 310 and operates in thesame manner as illustrated in FIGS. 57A, 58A-58B. It may also beappreciated that other mechanisms may be used for manipulating the locklines 92 and proximal element lines 90, such as including buttons,springs, levers and knobs.

G. Actuator Rod Control and Handle

The actuator rod 64 may be manipulated using the actuator rod control314 and the actuator rod handle 316. FIG. 59 provides a cross-sectionalview of a portion of the handle 304 which includes the actuator rodcontrol 314 and the actuator rod handle 316. The actuator rod handle 316is located at the proximal end of the handle 314. The actuator rodhandle 316 is fixedly attached to the proximal end of the actuator rod64. The actuator rod 64 is inserted through a collet 426 which isdisposed within a holder 428 as shown. The holder 428 has externalthreads 434 which mate with internal threads 432 of the actuator rodcontrol 314. Thus, rotation of the actuator rod control 314 causes theholder 428 to translate along the actuator rod control 314 by action ofthe threading, as will be described in more detail below. The actuatorrod control 314 is rotatably coupled with the main body 308 of thehandle 304 and is held in place by a lip 430.

Referring to FIG. 59A, the actuator rod control 314 may be manuallyrotated in a clockwise or counter clockwise direction, as indicated byarrow 436. Rotation of the actuator rod control 314 translates (extendsor retracts) the actuator rod 64 to manipulate the distal elements 18 ofthe fixation device 14. Specifically, rotation of the actuator rodcontrol 314 causes the external threads 434 of the adjacent holder 428to translate along the mated internal threads 432 of the actuator rodcontrol 314. Rotation of the holder 428 itself is prevented by holdingpins 424 which protrude from the holder 428 and nest into grooves 438 inthe main body 308 of the handle 304. As the holder 428 translates, eachholding pin 424 translates along its corresponding groove 438. Since thecollet 426 is attached to the holder 428, the collet 426 translatesalong with the holder 428. To simultaneously translate the actuator rod64, the actuator rod 64 is removably attached to the collet 426 by a pin422. The pin 422 may have any suitable form, including a clip-shapewhich partially wraps around the collet 426 as illustrated in FIG. 59.Thus, rotation of the actuator rod control 314 provides fine control oftranslation of the actuator rod 64 and therefore fine control ofpositioning the distal elements 18.

Referring to FIG. 59B, removal of the pin 422, as shown, allowsdisengagement of the actuator rod handle 316 and fixedly attachedactuator rod 64 from the collet 426. Once disengaged, the actuator rod64 may be rotated, as indicated by arrow 440, by manually rotating theactuator rod handle 316. As described previously, rotation of theactuator rod 64 engages or disengages the threaded joiner 332 of thedelivery catheter 300 from the threaded stud 74 of the fixation device14. This is used to attach or detach the fixation device 14 from thedelivery catheter 300. In addition, when the actuator rod 64 is in thedisengaged state, the actuator rod 64 may optionally be retracted andoptionally removed from the catheter 300 by pulling the actuator rodhandle 316 and withdrawing the actuator rod 64 from the handle 304.

Depending on the application, the location of the target site, and theapproach selected, the devices of the invention may be modified in wayswell known to those of skill in the art or used in conjunction withother devices that are known in the art. For example, the deliverycatheter may be modified in length, stiffness, shape and steerabilityfor a desired application. Likewise, the orientation of the fixationdevice relative to the delivery catheter may be reversed or otherwisechanged. The actuation mechanisms may be changed to be driven inalternate directions (push to open, pull to close, or pull to open, pushto close). Materials and designs may be changed to be, for example, moreflexible or more rigid. And, the fixation device components may bealtered to those of different size or shape. Further, the deliverycatheter of the present invention may be used to deliver other types ofdevices, particularly endovascular and minimally invasive surgicaldevices used in angioplasty, atherectomy, stent-delivery, embolicfiltration and removal, septal defect repair, tissue approximation andrepair, vascular clamping and ligation, suturing, aneurysm repair,vascular occlusion, and electrophysiological mapping and ablation, toname a few. Thus, the delivery catheter of the present invention may beused for applications in which a highly flexible, kink-resistant deviceis desirable with high compressive, tensile and torsional strength.

V. Multi-Catheter Guiding System

A. Overview of Guiding System

Referring to FIG. 60, an embodiment of a multi-catheter guiding system 1of the present invention is illustrated. The system 1 comprises an outerguide catheter 1000, having a proximal end 1014, a distal end 1016, anda central lumen 1018 therethrough, and an inner guide catheter 1020,having a proximal end 1024, distal end 1026 and central lumen 1028therethrough, wherein the inner guide catheter 1020 is positionedcoaxially within the central lumen 1018 of the outer guide catheter1000, as shown. The distal ends 1016, 1026 of catheters 1000, 1020,respectively, are sized to be passable to a body cavity, typicallythrough a body lumen such as a vascular lumen. Thus, the distal end 1016preferably has an outer diameter in the range of approximately 0.040 in.to 0.500 in., more preferably in the range of 0.130 in. to 0.320 in. Thecentral lumen 1018 is sized for the passage of the inner guide catheter1020; the distal end 1026 preferably has an outer diameter in the rangeof approximately 0.035 in. to 0.280 in., more preferably 0.120 in to0.200 in. The central lumen 1028 is sized for the passage of a varietyof devices therethrough. Therefore, the central lumen 1028 preferablyhas an inner diameter in the range of approximately 0.026 in. to 0.450in., more preferably in the range of 0.100 in. to 0.180 in.

FIG. 60 illustrates an interventional catheter 1030 positioned withinthe inner guide catheter 1020 which may optionally be included in system1, however other interventional devices may be used. The interventionalcatheter 1030 has a proximal end 1034 and a distal end 1036, wherein aninterventional tool 1040 is positioned at the distal end 1036. In thisembodiment, the interventional tool 1040 comprises a detachable fixationdevice or clip. Optionally, the interventional catheter 1030 may alsoinclude a nosepiece 1042 having a stop 1043, as shown. The stop 1043prevents the interventional tool 1040 from entering the central lumen1028 of the inner guide catheter 1020. Thus, the interventional catheter1030 may be advanced and retracted until the stop 1043 contacts thedistal end 1026 of the inner guiding catheter 1020 preventing furtherretraction. This may provide certain advantages during some procedures.It may be appreciated that in embodiments which include such a stop1043, the interventional catheter 1030 would be pre-loaded within theinner guide catheter 1020 for advancement through the outer guidingcatheter 1000 or both the interventional catheter 1030 and the innerguiding catheter 1020 would be pre-loaded into the outer guidingcatheter 1000 for advancement to the target tissue. This is because thestop 1043 prevents advancement of the interventional catheter 1030through the inner guiding catheter 1020.

The outer guide catheter 1000 and/or the inner guide catheter 1020 areprecurved and/or have steering mechanisms, embodiments of which will bedescribed later in detail, to position the distal ends 1016, 1026 indesired directions. Precurvature or steering of the outer guide catheter1000 directs the distal end 1016 in a first direction to create aprimary curve while precurvature and/or steering of the inner guidecatheter 1020 directs distal end 1026 in a second direction, differingfrom the first, to create a secondary curve. Together, the primary andsecondary curves form a compound curve. Advancement of theinterventional catheter 1030 through the coaxial guide catheters 1000,1020 guides the interventional catheter 1030 through the compound curvetoward a desired direction, usually in a direction which will allow theinterventional catheter 1030 to reach its target.

Steering of the outer guide catheter 1000 and inner guide catheter 1020may be achieved by actuation of one or more steering mechanisms.Actuation of the steering mechanisms is achieved with the use ofactuators which are typically located on handles connected with each ofthe catheters 1000, 1020. As illustrated in FIG. 60, handle 1056 isconnected to the proximal end 1014 of the outer guide catheter 1000 andremains outside of the patient's body during use. Handle 1056 includessteering actuator 1050 which may be used to bend, arc or reshape theouter guide catheter 1000, such as to form a primary curve. Handle 1057is connected to the proximal end (not shown) of the inner guide catheter1020 and may optionally join with handle 1056 to form one larger handle,as shown. Handle 1057 includes steering actuator 1052 which may be usedto bend, arc or reshape the inner guide catheter 1020, such as to form asecondary curve and move the distal end 1026 of the inner guide catheter1020 through an angle theta, as will be described in a later section.

In addition, locking actuators 1058, 1060 may be used to actuate lockingmechanisms to lock the catheters 1000, 1020 in a particular position.Actuators 1050, 1052, 1058, 1060 are illustrated as buttons, however itmay be appreciated that these and any additional actuators located onthe handles 1056, 1057 may have any suitable form including knobs,thumbwheels, levers, switches, toggles, sensors or other devices. Otherembodiments of the handles will be described in detail in a latersection.

In addition, the handle 1056 may include a numerical or graphicaldisplay 1061 of information such as data indicating the position thecatheters 1000, 1020, or force on actuators. It may also be appreciatedthat actuators 1050, 1052, 1058, 1060 and any other buttons or screensmay be disposed on a single handle which connects with both thecatheters 1000, 1020.

B. Example Positions

FIGS. 61A-61D illustrate examples of positions that the catheters 1000,1020 may hold. Referring to FIG. 61A, the outer guide catheter 1000 maybe precurved and/or steered into a position which includes a primarycurve 1100. The primary curve 1100 typically has a radius of curvature1102 in the range of approximately 0.125 in. to 1.000 in., preferably inthe range of approximately 0.250 in. to 0.500 in. or forms a curve inthe range of approximately 0° to 120°. As shown, when the positionincludes only a primary curve 1100, the distal end 16 lies in a singleplane X. An axis x, transversing through the center of the central lumen18 at the distal end 16, lies within plane X.

Referring to FIG. 61B, the inner guide catheter 1020 extends through thecentral lumen 1018 of the outer guide catheter 1000. The inner guidecatheter 1020 may be precurved and/or steered into a position whichincludes a secondary curve 1104. The secondary curve 1104 typically hasa radius of curvature 10600 in the range of approximately 0.050 in. to0.750 in., preferably in the range of approximately 0.125 in. to 0.250in. or forms a curve in the range of approximately 0° to 180°. Thesecondary curve 1104 can lie in the same plane as the primary curve1100, plane X, or it can lie in a different plane, such as plane Z asshown. In this example, plane Z is substantially orthogonal to plane X.Axis z, transversing through the center of the central lumen 1028 of theinner guide catheter 1020 at the distal end 1026, lies within plane Z.In this example, axis x and axis z are at substantially 90 degree anglesto each other; however, it may be appreciated that axis x and axis z maybe at any angle in relation to each other. Also, although in thisexample the primary curve 1100 and the secondary curve 1104 lie indifferent planes, particularly in substantially orthogonal planes, thecurves 1100, 1104 may alternatively lie in the same plane.

Referring now to FIG. 61C, the inner guide catheter 1020 may be furthermanipulated to allow the distal end 1026 to move through an angle theta1070. The angle theta 1070 is in the range of approximately −180° to+180°, typically in the range of −90° to +90°, possibly in the range of−60° to +60°, −45° to +45°, −30° to +30° or less. As shown, the angletheta 1070 lies within a plane Y. In particular, axis y, which runsthrough the center of the central lumen 1028 at the distal end 1026,forms the angle theta 1070 with axis z. In this example, plane Y isorthogonal to both plane X and plane Z. Axes x, y, z all intercept at apoint within the central lumen 1028 which also coincides with theintersection of planes X, Y, Z.

Similarly, FIG. 61D illustrates movement of the distal end 1026 throughan angle theta 1070 on the opposite side of axis z. Again, the angletheta 1070 is measured from the axis z to the axis y, which runs throughthe center of the central lumen 1016 at the distal end 1026. As shown,the angle theta 1070 lies in plane Y. Thus, the primary curve 1100,secondary curve 1104, and angle theta 1070 can all lie in differentplanes, and optionally in orthogonal planes. However, it may beappreciated that the planes within which the primary curve 1100,secondary curve 1104 and angle theta 1070 lie may be mutually dependentand therefore would allow the possibility that some of these lie withinthe same plane.

In addition, the outer guide catheter 1000 may be pre-formed and/orsteerable to provide additional curves or shapes. For example, asillustrated in FIG. 62A, an additional curve 1110 may be formed by theouter guide catheter 1000 proximal to the primary curve 1100. In thisexample, the curve 1110 provides lift or raises the distal end 1016 ofthe outer guide catheter 1000, which in turn raises the distal end 1026of the inner guide catheter 1020. Such lifting is illustrated in FIG.62B. Here, the system 1 is shown prior to lifting in dashed line whereinthe axis y′ passes through the intersection of axis z and axis x′. Afterapplication of curve 1110, the distal portion of the system 1 is liftedin the direction of axis z so that axis x′ is raised to axis x″ and axisy′ is raised to axis y″. This raises distal end 1026 to a desiredheight.

The articulated position of the multi-catheter guiding system 1illustrated in FIGS. 61A-61D and FIGS. 62A-62B is particularly usefulfor accessing the mitral valve. FIGS. 63A-63D illustrate a method ofusing the system 1 for accessing the mitral valve MV. To gain access tothe mitral valve, the outer guide catheter 1000 may be tracked over adilator and guidewire from a puncture in the femoral vein, through theinferior vena cava and into the right atrium. As shown in FIG. 63A, theouter guide catheter 1000 may be punctured through a fossa F in theinteratrial septum S. The outer guide catheter 1000 is then advancedthrough the fossa F and curved by the primary curve 1100 so that thedistal end 1016 is directed over the mitral valve MV. Again, it may beappreciated that this approach serves merely as an example and otherapproaches may be used, such as through the jugular vein, femoralartery, port access or direct access, to name a few. Positioning of thedistal end 1016 over the mitral valve MV may be accomplished byprecurvature of the outer guide catheter 1000, wherein the catheter 1000assumes this position when the dilator and guidewire are retracted,and/or by steering of the outer guide catheter 1000 to the desiredposition. In this example, formation of the primary curve 1100 moves thedistal end 1016 within a primary plane, corresponding to previous planeX, substantially parallel to the valve surface. This moves the distalend 1016 laterally along the short axis of the mitral valve MV, andallows the distal end 1016 to be centered over the opening O between theleaflets LF.

Referring to FIG. 63B, the inner guide catheter 1020 is advanced throughthe central lumen 1018 of the outer guide catheter 1000 and the distalend 1026 is positioned so that the central lumen 1028 is directed towardthe target tissue, the mitral valve MV. In particular, the central lumen1028 is to be directed toward a specific area of the mitral valve MV,such as toward the opening O between the valve leaflets LF, so that aparticular interventional procedure may be performed. In FIG. 63B, theinner guide catheter 1020 is shown in a position which includes asecondary curve 1104 in a secondary plane, corresponding to previousplane Z. Formation of the secondary curve 1104 moves the distal end 1026vertically and angularly between the commissures C, directing thecentral lumen 1028 toward the mitral valve MV. In this position aninterventional device or catheter 1030 which is passed through thecentral lumen 1028 would be directed toward and/or through the openingO. Although the primary curve 1100 and the secondary curve 1104 may bevaried to accommodate different anatomical variations of the valve MVand different surgical procedures, further adjustment may be desiredbeyond these two curvatures for proper positioning of the system 1.

Referring to FIG. 63C, the distal end 1026 of the inner guide catheter1020 may be positioned through an angle theta 1070. This moves thedistal end 1026 vertically and angularly through a theta plane,corresponding to previous plane Y. Movement of the distal end 1026through the angle theta 1070 in either direction is shown in dashed linein FIG. 63B. Such movement can be achieved by precurvature and/or bysteering of the catheter 1020. Consequently, the central lumen 1028 canbe directed toward the mitral valve MV within a plane which differs fromthe secondary plane. After such movements, the inner guide catheter 1020will be in a position so that the opening of the central lumen 1028 atthe end 1016 faces the desired direction. In this case, the desireddirection is toward the center of and orthogonal to the mitral valve.

In some instances, it is desired to raise or lower the distal end 1026so that it is at a desired height in relation to the mitral valve MV.This may be accomplished by precurvature and/or by steering of the outerguide catheter 1000 to form additional curve 1110. Generally this isused to lift the distal end 1026 above the mitral MV wherein suchlifting was illustrated in FIG. 62B.

When the curvatures in the catheters 1000, 1020 are formed by steeringmechanisms, the steering mechanisms may be locked in place by a lockingfeature. Locking can provide additional stiffness and stability in theguiding system 1 for the passage of interventional devices or catheters1030 therethrough, as illustrated in FIG. 60. The interventionalcatheter 1030 can be passed through the central lumen 1028 toward thetarget tissue, in this case the mitral valve MV. Positioning of thedistal end 1026 over the opening O, as described above, allows thecatheter 1030 to pass through the opening O between the leaflets LF ifdesired, as shown in FIG. 63D. At this point, any desired procedure maybe applied to the mitral valve for correction of regurgitation or anyother disorder.

C. Steering Mechanisms

As described previously, the curvatures may be formed in the catheters1000, 1020 by precurving, steering or any suitable means. Precurvinginvolves setting a specific curvature in the catheter prior to usage,such as by heat setting a polymer or by utilizing a shape-memory alloy.Since the catheters are generally flexible, loading of the catheter on aguidewire, dilator obturator or other introductory device straightensthe catheter throughout the curved region. Once the catheter ispositioned in the anatomy, the introductory device is removed and thecatheter is allowed to relax back into the precurved setting.

To provide a higher degree of control and variety of possiblecurvatures, steering mechanisms may be used to create the curvatures andposition the catheters. In some embodiments, the steering mechanismscomprise cables or pullwires within the wall of the catheter. As shownin FIG. 64A, the outer guide catheter 1000 may include a pullwire 1120slidably disposed in lumens within the wall of the catheter 1000extending to the distal end 1016. By applying tension to the pullwire1120 in the proximal direction, the distal end 1016 curves in thedirection of the pullwire 1120 as illustrated by arrow 1122. Likewise,as shown in FIG. 64A, placement of the pullwire 1120 along the oppositeside of the catheter 1000 will allow the distal end 1016 to curve in theopposite direction, as illustrated by arrow 1124, when tension isapplied to the pullwire 1120. Thus, referring to FIG. 64C, diametricallyopposing placement of pullwires 1120 within the walls of the catheter1000 allows the distal end 1016 to be steered in opposite directions.This provides a means of correcting or adjusting a curvature. Forexample, if tension is applied to one pullwire to create a curvature,the curvature may be lessened by applying tension to the diametricallyopposite pullwire. Referring now to FIG. 64D, an additional set ofopposing pullwires 1120′ may extend within the wall of the catheter 1000as shown. This combination of pullwires 1120, 1120′ allows curvature ofthe distal end in at least four directions illustrated by arrows 1122,1124, 1126, 1128. In this example, pullwires 1120 create the primarycurve 1100 of the outer guide catheter 1000 and the pullwires 1120′create the lift. It may be appreciated that FIGS. 64A-64D also pertainto the inner guide catheter 1020. For example, in FIG. 64D, pullwires1120 may create the secondary curve 1104 of the inner guide catheter1020 and the pullwires 1120′ create the angle theta 1070.

Such pullwires 1120 and/or pullwires 1120′ and associated lumens may beplaced in any arrangement, singly or in pairs, symmetrically ornonsymmetrically and any number of pullwires may be present. This mayallow curvature in any direction and about various axes. The pullwires1120, 1120′ may be fixed at any location along the length of thecatheter by any suitable method, such as gluing, tying, soldering, orpotting, to name a few. When tension is applied to the pullwire, thecurvature forms from the point of attachment of the pullwire toward theproximal direction. Therefore, curvatures may be formed throughout thelength of the catheter depending upon the locations of the points ofattachment of the pullwires. Typically, however, the pullwires will beattached near the distal end of the catheter, optionally to an embeddedtip ring 280, illustrated in FIG. 64E. As shown, the pullwire 1120passes through an orifice 286 in the tip ring 280, forms a loop shapeand then passes back through the orifice 286 and travels back up throughthe catheter wall (not shown). In addition, the lumens which house thepullwires may be straight, as shown in FIGS. 64A-64D, or may be curved.

D. Catheter Construction

The outer guide catheter 1000 and inner guide catheter 1020 may have thesame or different construction which may include any suitable materialor combination of materials to create the above described curvatures.For clarity, the examples provided will be in reference to the outerguide catheter 1000, however it may be appreciated that such examplesmay also apply to the inner guide catheter 1020.

In embodiments in which the catheter is precurved rather than steerableor in addition to being steerable, the catheter 1000 may be comprised ofa polymer or copolymer which is able to be set in a desired curvature,such as by heat setting. Likewise, the catheter 1000 may be comprised ofa shape-memory alloy.

In embodiments in which the catheter is steerable, the catheter 1000 maybe comprised of one or more of a variety of materials, either along thelength of the catheter 1000 or in various segments. Example materialsinclude polyurethane, Pebax, nylon, polyester, polyethylene, polyimide,polyethylenetelephthalate (PET), polyetheretherketone (PEEK). Inaddition, the walls of the catheter 1000 may be reinforced with avariety of structures, such as metal braids or coils. Suchreinforcements may be along the length of the catheter 1000 or invarious segments.

For example, referring to FIG. 65A, the catheter 1000 may have aproximal braided segment 1150, a coiled segment 1152 and distal braidedsegment 1154. The proximal braided segment 1150 provides increasedcolumn strength and torque transmission. The coiled segment 1152provides increased steerability. The distal braided segment 1154provides a blend of steerability and torque/column strength. In anotherexample, referring to FIG. 65B, the outer guiding catheter 1000 has aproximal double-layer braided segment 1151 and a distal braided segment1154. Thus, the proximal double-layer segment 1151 comprises amulti-lumen tube 1160 (having steering lumens 1162 for pullwires, distalends of the steering lumens 1162 optionally embedded with stainlesssteel coils for reinforcement, and a central lumen 1163), an innerbraided layer 1164, and an outer braided layer 1166, as illustrated inthe cross-sectional view of FIG. 65C. Similarly, FIG. 65D provides across-sectional view of the distal braided segment 1154 comprising themulti-lumen tube 1160 and a single braided layer 1168. In a furtherexample, referring to FIG. 65E, the inner guiding catheter 1020comprises a multi-lumen tube 1160 without reinforcement at its proximalend, a single braided layer middle segment 1170 and a single braidedlayer distal segment 1171. Each of the single braided layer segments1170, 1171 have a multi-lumen tube 1160 and a single layer of braiding1168, as illustrated in cross-sectional view FIG. 65F. However, thesegments 1170, 1171 are comprised of polymers of differing durometers,typically decreasing toward the distal end.

FIG. 65G illustrates an other example of a cross-section of a distalsection of an outer guiding catheter 1000. Here, layer 1130 comprises 55D Pebax and has a thickness of approximately 0.0125 in. Layer 1131comprises a 30 ppi braid and has a thickness of approximately 0.002 in.by 0.0065 in. Layer 1132 comprises 55 D Pebax and has a thickness ofapproximately 0.006 in. Layer 1133 comprises 30 ppi braid and has athickness of approximately 0.002 in by 0.0065 in. And finally, layer1134 comprises Nylon 11 and includes steering lumens for approximately0.0105 in. diameter pullwires 1120. Central lumen 1163 is of sufficientsize for passage of devices.

FIGS. 65H-65I illustrate additional examples of cross-sections of aninner guiding catheter 1020, FIG. 65I illustrating a cross-section of aportion of the distal end and FIG. 65I illustrating a cross-section of amore distal portion of the distal end. Referring to FIG. 65H, layer 1135comprises 40 D polymer and has a thickness of approximately 0.0125 in.Layer 1136 comprises a 30 ppi braid and has a thickness of approximately0.002 in. by 0.0065 in. Layer 1137 comprises 40 D polymer and has athickness of approximately 0.006 in. Layer 1138 comprises a 40 D polymerlayer and has a thickness of approximately 0.0035 in. And finally, layer1139 comprises a 55 D liner. In addition, coiled steering lumens areincluded for approximately 0.0105 in. diameter pullwires 1120. And,central lumen 1163 is of sufficient size for passage of devices.Referring to FIG. 65I, layer 1140 comprises a 40 D polymer, layer 1141comprises a 35 D polymer, layer 1142 comprises a braid and layer 1143comprises a liner. In addition, coiled steering lumens 1144 are includedfor pullwires. And, central lumen 1163 is of sufficient size for passageof devices.

FIGS. 66A-66C illustrate an embodiment of a keying feature which may beincorporated into the catheter shafts. The keying feature is used tomaintain relationship between the inner and outer guide catheters toassist in steering capabilities. As shown in FIG. 66A, the inner guidecatheter 1020 includes one or more protrusions 1400 which extendradially outwardly. In this example, four protrusions 1400 are present,equally spaced around the exterior of the catheter 1020. Likewise, theouter guide catheter 1000 includes corresponding notches 1402 whichalign with the protrusions 1400. Thus, in this example, the catheter1000 includes four notches equally spaced around its central lumen 1018.Thus, the inner guide catheter 1020 is able to be translated within theouter guide catheter 1000, however rotation of the inner guide catheter1020 within the outer guide catheter 1000 is prevented by the keyingfeature, i.e. the interlocking protrusions 1400 and notches 1402. Suchkeying helps maintain a known correlation of position between the innerguide catheter 1020 and outer guide catheter 1000. Since the inner andouter guide catheters 1020, 1000 form curvatures in differentdirections, such keying is beneficial to ensure that the compoundcurvature formed by the separate curvatures in the inner and outer guidecatheters 1020, 1000 is the compound curvature that is anticipated.Keying may also increase stability wherein the curvatures remain inposition reducing the possibility of compensating for each other.

FIG. 66B illustrates a cross-sectional view of the outer guidingcatheter 1000 of FIG. 66A. Here, the catheter 1000 includes a notchedlayer 1404 along the inner surface of central lumen 1018. The notchedlayer 1404 includes notches 1402 in any size, shape, arrangement andnumber. Optionally, the notched layer 1404 may include lumens 1406,typically for passage of pullwires 1120. However, the lumens 1406 mayalternatively or in addition be used for other uses. It may also beappreciated that the notched layer 1404 may be incorporated into thewall of the catheter 1000, such as by extrusion, or may be a separatelayer positioned within the catheter 1000. Further, it may beappreciated that the notched layer 1404 may extend the entire length ofthe catheter 1000 or one or more portions of the length of the catheter1000, including simply a small strip at a designated location along thelength of the catheter 1000.

FIG. 66C illustrates a cross-sectional view of the inner guidingcatheter 1020 of FIG. 66A. Here, the catheter 1020 includes protrusions1400 along the outer surface of the catheter 1020. The protrusions 1400may be of any size, shape, arrangement and number. It may be appreciatedthat the protrusions 1400 may be incorporated into the wall of thecatheter 1020, such as by extrusion, may be included in a separatecylindrical layer on the outer surface of the catheter 1020, or theprotrusions 1400 may be individually adhered to the outer surface of thecatheter 1020. Further, it may be appreciated that the protrusions 1400may extend the entire length of the catheter 1000 or one or moreportions of the length of the catheter 1020, including simply a smallstrip at a designated location along the length of the catheter 1020.

Thus, the keying feature may be present along one or more specificportions of the catheters 1000, 1020 or may extend along the entirelength of the catheters 1000, 1020. Likewise, the notches 1402 mayextend along the entire length of the outer guiding catheter 1020 whilethe protrusions 1400 extend along discrete portions of the inner guidingcatheter 1000 and vice versa. It may further be appreciated that theprotrusions 1400 may be present on the inner surface of the outerguiding catheter 1000 while the notches 1402 are present along the outersurface of the inner guiding catheter 1020.

Alternatively or in addition, one or more steerable portions of thecatheter 1000 may comprise a series of articulating members 1180 asillustrated in FIG. 67A. Exemplary embodiments of steerable portions ofcatheters comprising such articulating members 1180 are described inU.S. patent application Ser. No. 10/441,753 incorporated herein byreference for all purposes. FIG. 67B illustrates the outer guidecatheter 1000 having a steerable portion comprising articulating members1180 at its distal end 1016.

Briefly, referring to FIG. 67A, each articulating member 1180 may haveany shape, particularly a shape which allows interfitting or nesting asshown. In addition, it is desired that each member 1180 have thecapability of independently rotating against an adjacent articulatingmember 1180. In this embodiment, the articulating members 1180 compriseinterfitting domed rings 1184. The domed rings 1184 each include a base1188 and a dome 1186. The base 1188 and dome 1186 have a hollow interiorwhich, when the domed rings 1184 are interfit in a series, forms acentral lumen 1190. In addition, the dome 1186 allows each articulatingmember 1180 to mate against an inner surface of an adjacent domed ring1184.

The interfitting domed rings 1184 are connected by at least one pullwire1120. Such pullwires typically extend through the length of the catheter1000 and at least one of the interfitting domed rings 1184 to a fixationpoint where the pullwire 1120 is fixedly attached. By applying tensionto the pullwire 1120, the pullwire 1120 arcs the series of interfittingdomed rings 1184 proximal to the attachment point to form a curve. Thus,pulling or applying tension on at least one pullwire, steers or deflectsthe catheter 1000 in the direction of that pullwire 1120. By positioningvarious pullwires 1120 throughout the circumference of the domed rings1184, the catheter 1000 may be directed in any number of directions.

Also shown in FIG. 67A, each interfitting domed ring 1184 may compriseone or more pullwire lumens 1182 through which the pullwires 1120 arethreaded. Alternatively, the pullwires 1120 may be threaded through thecentral lumen 1190. In any case, the pullwires are attached to thecatheter 1000 at a position where a desired curve is to be formed. Thepullwires 1120 may be fixed in place by any suitable method, such assoldering, gluing, tying, welding or potting, to name a few. Suchfixation method is typically dependent upon the materials used. Thearticulating members 1180 may be comprised of any suitable materialincluding stainless steel, various metals, various polymers orco-polymers. Likewise the pullwires 1120 may be comprised of anysuitable material such as fibers, sutures, metal wires, metal braids, orpolymer braids.

E. Handles

As mentioned previously, manipulation of the guide catheters 1000, 1020is achieved with the use of handles 1056, 1057 attached to the proximalends of the catheters 1000, 1020. FIG. 68 illustrates a preferredembodiment of handles 1056, 1057. As shown, handle 1056 is attached tothe proximal end 1014 of outer guide catheter 1000 and handle 1057 isattached to the proximal end 1024 of inner guide catheter 1020. Innerguide catheter 1020 is inserted through handle 1056 and is positionedcoaxially within outer guide catheter 1000. In this embodiment, thehandles 1056, 1057 are not linked together as shown in the embodimentillustrated in FIG. 60. It may be appreciated that such handles 1056,1057 may alternatively be connected by external connecting rods, bars orplates or by an additional external stabilizing base. An embodiment of astabilizing base will be described in a later section. Referring back toFIG. 68, interventional catheter is inserted through handle 1057 and ispositioned coaxially within inner guide catheter 1020 and outer guidecatheter 1000.

Each handle 1056, 1057 includes two steering knobs 1300 a, 1300 bemerging from a handle housing 1302 for manipulation by a user. Steeringknobs 1300 a are disposed on a side of the housing 1302 and steeringknobs 1300 b are disposed on a face of the housing 1302. However, it maybe appreciated that such placement may vary based on a variety offactors including type of steering mechanism, size and shape of handle,type and arrangement of parts within handle, and ergonomics to name afew.

FIG. 69 illustrates the handles 1056, 1057 of FIG. 68 with a portion ofthe housing 1302 removed to reveal the assemblies of the handles. Eachknob 1300 a, 1300 b controls a steering mechanism which is used to forma curvature in the attached catheter. Each steering mechanism includes ahard stop gear assembly 1304 and a friction assembly 1306. Tension isapplied to one or more pullwires by action of the hard stop gearassembly to form a curve in a catheter. Tension is maintained by thefriction assembly. When tension is released from the one or morepullwires the catheter returns to a straightened position.

FIG. 70 illustrates steering mechanisms within a handle wherein thehousing 1302 is removed for clarity. Here, steering knob 1300 a isattached to a hard stop gear assembly 1304 and a friction assembly (notin view) and steering knob 1300 b is attached to a separate hard stopgear assembly 1304 and friction assembly 1306. Steering knob 1300 a isattached to a knob post 1318 which passes through a base 1308,terminating in a knob gear wheel 1310. The knob gear wheel 1310 actuatesthe hard stop gear assembly 1304, thereby applying tension to one ormore pullwires 1120.

The knob gear wheel 1310 is a toothed wheel that engages a disk gearwheel 1312. Rotation of the steering knob 1300 a rotates the knob post1318 and knob gear wheel 1310 which in turn rotates the disk gear wheel1312. Rotation of the disk gear wheel 1312 applies tension to one ormore pullwires extending through the attached catheter, in this examplethe outer guiding catheter 1000. As shown, the outer guiding catheter1000 passes through the base 1308, wherein one or more pullwires 1120extending through the catheter 1000 are attached to the disk 1314. Suchattachment is schematically illustrated in FIG. 71. Catheter 1000 isshown passing through base 1308. A pullwire 1120 passing through asteering lumen 1162 in the catheter 1000 emerges from the wall of thecatheter 1000, passes through an aperture 1320 in the disk 1314 and isattached to an anchor peg 1316 on the disk 1314. Rotation of the disk1314 (indicated by arrow 1328) around disk post 1315 by action of thedisk gear wheel 1312, applies tension to the pullwire 1120 by drawingthe pullwire 1120 through the aperture 1320 and wrapping the pullwire1120 around the disk 1314 as it rotates. Additional rotation of the disk1314 applies increasing tension to the pullwire 1120. To limit theamount of tension applied to the pullwire 1120, to limit curvature ofthe catheter and/or to avoid possible breakage of the pullwire 1120, therotation of the disk 1314 may be restricted by hard stop peg 1322 whichis attached to the disk 1314 and extends into the base 1308.

FIGS. 72A-72B illustrate how the hard stop peg 1322 is used to restrictrotation of disk 1314. FIGS. 72A-72B provide a top view, wherein thedisk 1314 is disposed on the base 1308. The anchor peg 1316 is shownwith the pullwire 1120 thereattached. A groove 1326 is formed in thebase 1308 beneath the disk 1314 and forms an arc shape. The hard stoppeg 1322 extends from the disk 1314 into the groove 1326 in the base1308. Referring now to FIG. 72B, rotation of the disk 1314 around knobpost 1318, indicated by arrow 1330, draws the pullwire 1120 through theaperture 1320 as previously described, wrapping the pullwire 1120 aroundthe disk 1314. As the disk 1314 rotates, the hard stop peg 1322 followsalong the groove 1326, as shown. The disk 1314 continues rotating untilthe hard stop peg 1322 reaches a hard stop 1324. The hard stop 1324 ispositioned in the groove 1326 and prevents further passage of the hardstop peg 1322. Thus, disk 1314 rotation may be restricted to any degreeof rotation less than or equal to 360 degrees by positioning of the hardstop 1324.

In some instances, it is desired to restrict rotation of the disk 1314to a degree of rotation which is more than 360 degrees. This may beachieved with another embodiment of the hard stop gear assembly 1304.Referring now to FIGS. 73A-73B, a portion of such a hard stop gearassembly 1304 is shown. FIG. 73A illustrates the base 1308 and the diskpost 1315 positioned therethrough. Also shown in the base 1308 is anaperture 1334 through which the knob post 1318, knob gear wheel 1310 andfriction assembly 1306 pass, and a passageway 1336 through which thecatheter 1000 passes. In this embodiment of the hard stop gear assembly1304, a groove 1326 is also present in an arc shape around the disk post1315, however a ball 1332 is positioned in the groove 1326 rather than ahard stop peg 1322. Disk 1314 is positioned over the groove 1326 and theball 1332 as shown in FIG. 73B. The disk 1314, illustrated in FIG. 73C,has a groove 1356 in its surface which is positioned adjacent to thebase 1308, the groove 1356 having an arc shape similar to the groove1326 in the base 1308. The ball 1332 is not fixedly attached to the base1308 or the disk 1314 and is therefore free to move along the channelformed by the groove 1326 in the base 1308 and the groove in the disk1314.

FIGS. 74A-74F illustrate how rotation of the disk 1314 may be restrictedby the ball 1332 to a degree of rotation which is more than 360 degrees.FIGS. 74A-74F illustrate the groove 1326 in the base 1308 wherein thegroove 1326 has an arc shape around disk post 1315. The groove 1326 doesnot form a complete circle; a first groove end 1350 a and a secondgroove end 1350 b form a wall which prevent passage of the ball 1332. Itmay be appreciated that the groove ends 1350 a, 1350 b may be anydistance apart, shortening the length of the groove 1326 by any amount,and allowing the ball 1332 movement, and hence catheter deflection, tobe adjusted to any desired amount. To begin, referring to FIG. 74A, theball 1332 is positioned within the groove 1326 near the first groove end1350 a. The disk 1314 has a matching groove 1352 (shape illustrated indashed line) including a first groove end 1354 a and a second groove end1354 b. The disk 1314 is positioned over the ball 1332 so that the ball1332 is near the second groove end 1354 b.

Referring now to FIG. 74B, the disk 1314 may be rotated while the ball1332 remains in place. Here, the disk 1314 has rotated 90 degrees, asindicated by arrow 36000 and the position of the groove ends 1354 a,1354 b. Referring now to FIG. 74C, the disk 1314 may be further rotatedwhile the ball 1332 remains in place. Here, the disk 1314 has rotated270 degrees, as indicated by arrow 36000 and the position of the grooveends 1354 a, 1354 b. The disk 1314 may continue rotating to 360 degrees,as shown in FIG. 74D, indicated by arrow 36000. Here, the first grooveend 1354 a in the disk 1314 has contacted the ball 1332 and pushes theball 1332 along groove 1326 in the base. Referring now to FIG. 74E, thedisk 1314 may be further rotated while the ball 1332 is pushed along thegroove 1326 in the base 1308 by the first groove end 1354 a in the disk1314. Here, the disk 1314 is shown to have rotated 540 degrees.Referring to FIG. 74F, the disk 1314 rotates until the ball 1332 reachesthe second groove end 1350 b of the base 1308, providing a hard stop. Inthis position, the ball 1332 is held between the first groove end 1354 aof the disk 1314 and the second groove end 1350 b of the base 1308 andfurther rotation of the disk 1314 is prevented. Thus, the disk 1314 wasrotated approximately 660 degrees in this example. Any maximum degree ofrotation may be set by positioning of groove ends 1350 a, 1350 b and/orgroove ends 1354 a, 1354 b. Additionally, in some embodiments, rotationcan be limited by adding more than one ball 1332 to the groove 1326, forexample, two, three, four, five, six, seven, eight, nine, ten or moreballs may be used to limit travel and hence curvature.

It may be appreciated that one or more pullwires 1120 are attached tothe disk 1314 in a manner similar to that illustrated in FIG. 71.Therefore, as the disk 1314 rotates, around disk post 1315 by action ofthe disk gear wheel 1312, tension is applied to the pullwire 1120 bydrawing the pullwire 1120 through the aperture 1320 and wrapping thepullwire 1120 around the disk 1314 as it rotates. Additional rotation ofthe disk 1314 applies increasing tension to the pullwire 1120.Restriction of rotation as described above limits the amount of tensionapplied to the pullwire 1120, to limit curvature of the catheter and/orto avoid possible breakage of the pullwire 1120.

As mentioned, each steering mechanism includes at least a hard stop gearassembly 1304 and a friction assembly 1306. As described above, tensionis applied to one or more pullwires by action of the hard stop gearassembly to form a curve in a catheter. Tension is maintained by thefriction assembly. FIG. 75 illustrates an embodiment of a frictionassembly 1306. The friction assembly 1306 essentially holds a steeringknob, in this example steering knob 1300 b, and the associated knob post1318 in a rotated position. Here, rotation of the knob 1300 b and post1318 rotates attached knob gear wheel 1310. The knob gear wheel 1310actuates the hard stop gear assembly 1304, thereby applying tension toone or more pullwires 1120. The knob gear wheel 1310 is a toothed wheelthat engages a disk gear wheel 1312. Rotation of the steering knob 1300b rotates the knob post 1318 and knob gear wheel 1310 which in turnrotates the disk gear wheel 1312. Rotation of the disk gear wheel 1312applies tension to one or more pullwires extending through the attachedcatheter, in this example the outer guiding catheter 1000.

The steering knob 1300 b and knob post 1318 are held in a rotatedposition by friction provided by a frictional pad 1370. The frictionalpad 1370 is positioned between ring 1372 attached to the knob post 1318and a plate 1374 attached to the base 1308. The knob post 1318 extendsfrom the knob 1300 b through the ring 1372, the frictional pad 1370 andthen the plate 1374. The plate 1374 has internal threads which mate withthreads on the knob post 1318. As the knob post 1318 rotates, thethreads on the post 1318 advance through the threads on the plate 1374.This draws the ring 1372 closer to the plate 1374, compressing thefrictional pad 1370 therebetween. Frictional pad 1370 may be comprisedof any O-ring or sheet material with desirable frictional andcompressibility characteristics, such as silicone rubber, natural rubberor synthetic rubbers, to name a few. In preferred embodiments, an EPDMrubber O-ring is used. Reverse rotation of the knob post 1318 isresisted by friction of the frictional pad 1370 against the ring 1372.The higher the compression of the frictional pad 1370 the stronger thefrictional hold. Therefore, as the steering knob 1300 b is rotated andincreasing amounts of tension are applied to the pullwires 1120,increasing amounts of friction are applied to the ring 1372 to hold theknob 1300 b in place.

Manual reverse rotation of the steering knob 1300 b releases tension onthe pullwires 1120 and draws the ring 1372 away from the plate 1374thereby reducing the frictional load. When tension is released from thepullwires 1120 the catheter 1000 returns toward a straightened position.

It may be appreciated that each handle 1056, 1057 includes a steeringmechanism for each curve to be formed in the attached catheter. Thus, asshown in FIG. 69, handle 1056 includes a steering mechanism to form theprimary curve 1100 in outer guiding catheter 1000 and a steeringmechanism to form the additional curve 1110. Likewise, handle 1057includes a steering mechanism to form the secondary curve 1104 in innerguiding catheter 1020 and a steering mechanism to form the angle theta1070.

Some curves, such as the primary curve 1100, secondary curve 1104 andadditional curve 1110 each typically vary in curvature between astraight configuration and a curved configuration in a single direction.Such movement may be achieved with single set of a hard stop gearassembly 1304 and a friction assembly 1306. However, other curves, suchas the angle theta 1070, may be formed in two directions as shown inFIGS. 61C-61D. Such movement is achieved with two sets of the hard stopgear assembly 1304 and the friction assembly 1306, each set controllingcurvature in a single direction.

FIG. 75 illustrates the presence of an additional set of the frictionassembly 1306′. One or more pullwires 1120′, such as an opposing set asillustrated in FIG. 64D, extending within the wall of the catheter 1000are attached to the disk 1314′ in the same manner as pullwires 1120 areattached to disk 1314. The disks 1314, 1314′ are arranged so thatrotation of steering knob 1300 b in one direction applies tension to thepullwires 1120 via disk 1314 and rotation of steering knob 1300 b in theopposite direction applies tension to the pullwires 1120′ via disk1314′. Likewise, the additional friction assembly 1306′ is shown havinga ring 1372′ attached to the knob post 1318 and a frictional pad 1370′disposed between the ring 1372′ and the opposite side of the plate 1374.Therefore, as rotation of the steering knob 1300 b in the oppositedirection applies tension to the pullwires 1120′ via disk 1314′, thefrictional pad 1370′ applies tension to the ring 1372′ holding the knobpost 1318′ in place.

It may be appreciated that various other mechanisms may be used fortensioning and holding pullwires 1120 in place. Example mechanisms thatmay alternatively be used include clutches, ratchets, levers, knobs,rack and pinions, and deformable handles, to name a few.

F. Interventional System

FIG. 76 illustrates an embodiment of an interventional system 3 of thepresent invention. An embodiment of the multi-catheter guiding system 1of the present invention is shown comprising an outer guide catheter1000, having a proximal end 1014 and a distal end 1016, and an innerguide catheter 1020, having a proximal end 1024 and a distal end 1026,wherein the inner guide catheter 1020 is positioned coaxially within theouter guide catheter 1000, as shown. In addition, a hemostatic valve1090 is disposed within handle 1056 or external to handle 1056 as shownto provide leak-free sealing with or without the inner guide catheter1020 in place. The valve 1090 also prevents back bleeding and reducesthe possibility of air introduction when inserting the inner guidecatheter 1020 through the outer guide catheter 1000. An example of ahemostatic valve 1090 is illustrated in FIG. 76A, however any suitablevalve or hemostatic valve may be used to provide similar functions. InFIG. 76A, the valve 1090 has a first end 1091, a second end 1092 and alumen 1093 therethrough. The inner wall of lumen 1093 is preferablytapered toward end 1091 and may further include a plurality of taperedaxial channels configured to receive the protrusions 1400 on the innerguide catheter 1020. The first end 1091 is attached to the outer guidecatheter 1000 and the second end 1092 is free. Referring now back toFIG. 76, the distal ends 1016, 1026 of catheters 1000, 1020,respectively, are sized to be passable to a body cavity, typicallythrough a body lumen such as a vascular lumen.

To assist in inserting the fixation device 14 through a hemostatic valve1090, a fixation device introducer may be used. For example, when thefixation device 14 is loaded on a delivery catheter 300 and an innerguide catheter 1020, insertion of the fixation device 14, deliverycatheter 300 and inner guide catheter 1020 through an outer guidecatheter 1000 involves passing the fixation device 14 through ahemostatic valve 1090 on the outer guide catheter 1000. To reduce anytrauma to the fixation device 14 by the hemostatic valve 1090, afixation device introducer may be used. An embodiment of a fixationdevice introducer 1420 is illustrated in FIG. 76B. The introducer 1420includes a loading body 1422 and an insertion endpiece 1424. Thefixation device 14 is loaded into the loading body 1422 and into theinsertion endpiece 1424 to approximately the dashed line 1428. Theinsertion endpiece 1424 has a split end creating individual splitsections 1430, in this embodiment, four split sections 1430. Bycompressing the split sections 1430, the endpiece 1424 forms a taper.Such a taper is then inserted through a hemostatic valve 1090, so thatthe insertion endpiece 1424 creates a smooth passageway through thevalve for the fixation device 14. Once the insertion endpiece 1424 isinserted through the valve 1090, the fixation device 14, and attacheddelivery catheter 300 and inner guide catheter 1020, may then beadvanced through the fixation device introducer 1420. The fixationdevice introducer 1420 also includes a hemostatic valve within theloading body 1422 to prevent any backbleeding or leakage through theintroducer 1420.

Manipulation of the guide catheters 1000, 1020 is achieved with the useof handles 1056, 1057 attached to the proximal ends of the catheters1000, 1020. As shown, handle 1056 is attached to the proximal end 1014of outer guide catheter 1000 and handle 1057 is attached to the proximalend 1024 of inner guide catheter 1020. Inner guide catheter 1020 isinserted through handle 1056 and is positioned coaxially within outerguide catheter 1000.

An embodiment of the delivery catheter 300 of the present invention isinserted through handle 1057 and is positioned coaxially within innerguide catheter 1020 and outer guide catheter 1000. Therefore, ahemostatic valve 1090 is disposed within handle 1057 or external tohandle 1057 as shown to provide leak-free sealing with or without thedelivery catheter 300 in place. The valve 1090 functions as describedabove. The delivery catheter 300 includes a shaft 302, having a proximalend 322 and a distal end 324, and a handle 304 attached to the proximalend 322. A fixation device 14 is removably coupled to the distal end 324for delivery to a site within the body.

The outer guide catheter 1000 and/or the inner guide catheter 1020 areprecurved and/or have steering mechanisms to position the distal ends1016, 1026 in desired directions. Precurvature or steering of the outerguide catheter 1000 directs the distal end 1016 in a first direction tocreate a primary curve while precurvature and/or steering of the innerguide catheter 1020 directs distal end 1026 in a second direction,differing from the first, to create a secondary curve. Together, theprimary and secondary curves form a compound curve. Advancement of thedelivery catheter 300 through the coaxial guide catheters 1000, 1020guides the delivery catheter 300 through the compound curve toward adesired direction, usually in a direction which will position thefixation device 14 in a desired location within the body.

FIG. 77 illustrates portions of another embodiment of an interventionalsystem 3 of the present invention. Handles 1056, 1057 of themulti-catheter guiding system 1 of the present invention are shown. Eachhandle 1056, 1057 includes a set of steering knobs 1300 a, 1300 b, asshown. Manipulation of the guide catheters 1000, 1020 is achieved withthe use of the steering knobs 1300 a, 1300 b attached to the proximalends of the catheters 1000, 1020. Handle 304 of the delivery catheter300 is also shown, including the proximal element line handle 312, thelock line handle 310, the actuator rod control 314 and the actuator rodhandle 316, among other features. The handle 304 is supported by thesupport base 306 which is connected to the handle 1057.

It may be appreciated the above described systems 3 are not intended tolimit the scope of the present invention. The systems 3 may include anyor all of the components of the described invention. In addition, themulti-catheter guiding system 1 of the present invention may be used tointroduce other delivery catheters, interventional catheters or otherdevices. Likewise, the delivery catheter 300 may be introduced throughother introducers or guiding systems. Also, the delivery catheter 300may be used to deliver other types of devices to a target locationwithin the body, including endoscopic staplers, devices forelectrophysiology mapping or ablation, septal defect repair devices,heart valves, annuloplasty rings and others.

In addition, many of the components of the system 3 may include one ormore hydrophilic coatings. Hydrophilic coatings become slippery whenwet, eliminate the need for separate lubricants. Thus, such coatings maybe present on the multi-catheter guiding system, delivery catheter, andfixation device, including the proximal elements and distal elements, toname a few.

Further, the system 3 may be supported by an external stabilizer base1440, an embodiment of which is illustrated in FIG. 78. Stabilizer base1440 maintains the relative positions of the outer guide, inner guideand delivery catheter during a procedure. In this embodiment, the base1440 comprises a platform 1442 having a planar shape for positioning onor against a flat surface, such as a table or benchtop. The base 1440further includes a pair of handle holders 1444, 1448, each attached tothe platform 1442 and extending upwardly from the platform 1442, eitherangularly or perpendicularly. Handle holder 1444 includes a notch 1446for holding the outer guiding catheter 1000, as illustrated in FIG. 79,thereby supporting the handle 1056. FIG. 79 shows the handle 1056attached to the outer guiding catheter 1000 positioned so that theproximal end 1014 of the outer guiding catheter 1000 rests in the notch1446. Referring back to FIG. 78, handle holder 1448 includes an elongateportion 1452 having a trough 1450 and a hooked end 1454. As shown inFIG. 80, handle 1057 rests on the elongate portion 1452 and the handle304 rests on hooked end 1454 so that the inner guiding catheter 1020extends from the handle 1057 to the handle 1056 and continues on withinouter guiding catheter 1000. The handle 304 is additionally supported bysupport base 306, as shown.

It may be appreciated that the stabilizer base 1440 may take a varietyof forms and may include differences in structural design to accommodatevarious types, shapes, arrangements and numbers of handles.

G. Kits

Referring now to FIG. 81, kits 1500 according to the present inventioncomprise any of the components described in relation to the presentinvention. The kits 1500 may include any of the components describedabove, such as the outer guide catheter 1000 including handle 1056, theinner guide catheter 1020 including handle 1057, the delivery catheter300 and the fixation device 14 and instructions for use IFU. Optionally,any of the kits may further include any other system componentsdescribed above, such as various interventional tools 1040, orcomponents associated with positioning a device in a body lumen, such asa guidewire 1202, dilator 1206 or needle 1204. The instructions for useIFU will set forth any of the methods as described above, and all kitcomponents will usually be packaged together in a pouch 1505 or otherconventional medical device packaging. Usually, those kit componentswhich will be used in performing the procedure on the patient will besterilized and maintained within the kit. Optionally, separate pouches,bags, trays or other packaging may be provided within a larger package,where the smaller packs may be opened separately to separately maintainthe components in a sterile fashion.

While the foregoing is a complete description of the preferredembodiments of the invention, various alternatives, substitutions,additions, modifications, and equivalents are possible without departingfrom the scope of the invention. For example, in many of theabove-described embodiments, the invention is described in the contextof approaching a valve structure from the upstream side—that is, theatrial side in the case of a mitral valve. It should be understood thatany of the foregoing embodiments may be utilized in other approaches aswell, including from the ventricular or downstream side of the valve, aswell as using surgical approaches through a wall of the heart. Moreover,the invention may be used in the treatment of a variety of other tissuestructures besides heart valves, and will find usefulness in a varietyof tissue approximation, attachment, closure, clamping and ligationapplications, some endovascular, some endoscopic, and some opensurgical.

Again, although the foregoing invention has been described in somedetail by way of illustration and example, for purposes of clarity ofunderstanding, it will be obvious that various alternatives,modifications and equivalents may be used and the above descriptionshould not be taken as limiting in scope of the invention which isdefined by the appended claims.

What is claimed is:
 1. A fixation device for engaging tissue comprising:a coupling member having a first branch and a second branch, the firstbranch and the second branch being attached at a first end of thecoupling member and being bifurcated at a second end of the couplingmember, opposite the first end of the coupling member, such that thefirst and the second branch are configured to move independently, a pairof proximal gripping elements operably coupled with the coupling member,each of the gripping elements having a first end attached to the firstend of the coupling member, a free end opposite the first end, and agripping surface therebetween for gripping the tissue, the first endsbeing movably coupled together such that the gripping elements aremoveable between a first position wherein the free ends are spaced apartwith the gripping surfaces generally facing away from each other, and asecond position wherein the free ends are separated even further apart;and a pair of distal fixation elements operably coupled with thecoupling member, each of the fixation elements having a first endattached to the first end of the coupling member, a free end oppositethe first end, and an engagement surface therebetween for engaging thetissue, the first ends being movably coupled together such that thefixation elements are moveable between an open position wherein the freeends are spaced apart and a closed position wherein the free ends arecloser together with the engagement surfaces generally facing eachother.
 2. The fixation device of claim 1, further comprising: a sheathconfigured to move with respect to the coupling member, whereby thesheath is configured to coaxially surround the coupling member.
 3. Thefixation device of claim 2, wherein the first branch and the secondbranch at the second end of the coupling member are adjacently disposedwhen the sheath is coaxially disposed around the first branch and thesecond branch, and the first branch and the second branch at the secondend of the coupling member are configured to move away from each otherwhen the sheath is not coaxially surrounding the first branch and thesecond branch.
 4. The fixation device of claim 3, wherein the sheathincludes a collar having a groove, the groove configured to contact aprotrusion on the sheath when the sheath is coaxially disposed aroundthe coupling member.
 5. The fixation device of claim 3, wherein thegripping elements and the fixation elements are in the first positionand the closed position, respectively, when the sheath is coaxiallydisposed around the first branch and the second branch, and the grippingelements and the fixation elements are in the second position and theopen position when the sheath is not coaxially disposed around the firstbranch and the second branch.
 6. The fixation device of claim 1, whereinthe first branch and the second branch are biased away from each otherat the second end of the coupling member.